Implement resolutions of LWG 2399, 2400 and 2401.
[gcc.git] / libstdc++-v3 / include / bits / random.h
index 8a21ae55da7dc66634976bf63f305d17a95c8a73..774f726d0a6410db71f3c75936f3aebf22042c3c 100644 (file)
@@ -1,6 +1,6 @@
 // random number generation -*- C++ -*-
 
-// Copyright (C) 2009 Free Software Foundation, Inc.
+// Copyright (C) 2009-2014 Free Software Foundation, Inc.
 //
 // This file is part of the GNU ISO C++ Library.  This library is free
 // software; you can redistribute it and/or modify it under the
 /**
  * @file bits/random.h
  *  This is an internal header file, included by other library headers.
- *  You should not attempt to use it directly.
+ *  Do not attempt to use it directly. @headername{random}
  */
 
+#ifndef _RANDOM_H
+#define _RANDOM_H 1
+
 #include <vector>
 
-namespace std
+namespace std _GLIBCXX_VISIBILITY(default)
 {
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   // [26.4] Random number generation
 
   /**
-   * @addtogroup std_random Random Number Generation
+   * @defgroup random Random Number Generation
+   * @ingroup numerics
+   *
    * A facility for generating random numbers on selected distributions.
    * @{
    */
@@ -51,13 +57,15 @@ namespace std
     _RealType
     generate_canonical(_UniformRandomNumberGenerator& __g);
 
-  class seed_seq;
+_GLIBCXX_END_NAMESPACE_VERSION
 
   /*
    * Implementation-space details.
    */
   namespace __detail
   {
+  _GLIBCXX_BEGIN_NAMESPACE_VERSION
+
     template<typename _UIntType, size_t __w,
             bool = __w < static_cast<size_t>
                          (std::numeric_limits<_UIntType>::digits)>
@@ -68,18 +76,86 @@ namespace std
       struct _Shift<_UIntType, __w, true>
       { static const _UIntType __value = _UIntType(1) << __w; };
 
-    template<typename _Tp, _Tp __a, _Tp __c, _Tp __m, bool>
-      struct _Mod;
+    template<int __s,
+            int __which = ((__s <= __CHAR_BIT__ * sizeof (int))
+                           + (__s <= __CHAR_BIT__ * sizeof (long))
+                           + (__s <= __CHAR_BIT__ * sizeof (long long))
+                           /* assume long long no bigger than __int128 */
+                           + (__s <= 128))>
+      struct _Select_uint_least_t
+      {
+       static_assert(__which < 0, /* needs to be dependent */
+                     "sorry, would be too much trouble for a slow result");
+      };
+
+    template<int __s>
+      struct _Select_uint_least_t<__s, 4>
+      { typedef unsigned int type; };
+
+    template<int __s>
+      struct _Select_uint_least_t<__s, 3>
+      { typedef unsigned long type; };
+
+    template<int __s>
+      struct _Select_uint_least_t<__s, 2>
+      { typedef unsigned long long type; };
+
+#ifdef _GLIBCXX_USE_INT128
+    template<int __s>
+      struct _Select_uint_least_t<__s, 1>
+      { typedef unsigned __int128 type; };
+#endif
+
+    // Assume a != 0, a < m, c < m, x < m.
+    template<typename _Tp, _Tp __m, _Tp __a, _Tp __c,
+            bool __big_enough = (!(__m & (__m - 1))
+                                 || (_Tp(-1) - __c) / __a >= __m - 1),
+             bool __schrage_ok = __m % __a < __m / __a>
+      struct _Mod
+      {
+       typedef typename _Select_uint_least_t<std::__lg(__a)
+                                             + std::__lg(__m) + 2>::type _Tp2;
+       static _Tp
+       __calc(_Tp __x)
+       { return static_cast<_Tp>((_Tp2(__a) * __x + __c) % __m); }
+      };
+
+    // Schrage.
+    template<typename _Tp, _Tp __m, _Tp __a, _Tp __c>
+      struct _Mod<_Tp, __m, __a, __c, false, true>
+      {
+       static _Tp
+       __calc(_Tp __x);
+      };
+
+    // Special cases:
+    // - for m == 2^n or m == 0, unsigned integer overflow is safe.
+    // - a * (m - 1) + c fits in _Tp, there is no overflow.
+    template<typename _Tp, _Tp __m, _Tp __a, _Tp __c, bool __s>
+      struct _Mod<_Tp, __m, __a, __c, true, __s>
+      {
+       static _Tp
+       __calc(_Tp __x)
+       {
+         _Tp __res = __a * __x + __c;
+         if (__m)
+           __res %= __m;
+         return __res;
+       }
+      };
 
-    // Dispatch based on modulus value to prevent divide-by-zero compile-time
-    // errors when m == 0.
-    template<typename _Tp, _Tp __a, _Tp __c, _Tp __m>
+    template<typename _Tp, _Tp __m, _Tp __a = 1, _Tp __c = 0>
       inline _Tp
       __mod(_Tp __x)
-      { return _Mod<_Tp, __a, __c, __m, __m == 0>::__calc(__x); }
+      { return _Mod<_Tp, __m, __a, __c>::__calc(__x); }
 
-    typedef __gnu_cxx::__conditional_type<(sizeof(unsigned) == 4),
-                   unsigned, unsigned long>::__type _UInt32Type;
+    /* Determine whether number is a power of 2.  */
+    template<typename _Tp>
+      inline bool
+      _Power_of_2(_Tp __x)
+      {
+       return ((__x - 1) & __x) == 0;
+      };
 
     /*
      * An adaptor class for converting the output of any Generator into
@@ -88,6 +164,8 @@ namespace std
     template<typename _Engine, typename _DInputType>
       struct _Adaptor
       {
+       static_assert(std::is_floating_point<_DInputType>::value,
+                     "template argument not a floating point type");
 
       public:
        _Adaptor(_Engine& __g)
@@ -95,50 +173,37 @@ namespace std
 
        _DInputType
        min() const
-       {
-         if (is_integral<_DInputType>::value)
-           return _M_g.min();
-         else
-           return _DInputType(0);
-       }
+       { return _DInputType(0); }
 
        _DInputType
        max() const
-       {
-         if (is_integral<_DInputType>::value)
-           return _M_g.max();
-         else
-           return _DInputType(1);
-       }
+       { return _DInputType(1); }
 
        /*
         * Converts a value generated by the adapted random number generator
         * into a value in the input domain for the dependent random number
         * distribution.
-        *
-        * Because the type traits are compile time constants only the
-        * appropriate clause of the if statements will actually be emitted
-        * by the compiler.
         */
        _DInputType
        operator()()
        {
-         if (is_integral<_DInputType>::value)
-           return _M_g();
-         else
-           return generate_canonical<_DInputType,
-                                     numeric_limits<_DInputType>::digits,
-                                     _Engine>(_M_g);
+         return std::generate_canonical<_DInputType,
+                                   std::numeric_limits<_DInputType>::digits,
+                                   _Engine>(_M_g);
        }
 
       private:
        _Engine& _M_g;
       };
+
+  _GLIBCXX_END_NAMESPACE_VERSION
   } // namespace __detail
 
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
   /**
-   * @addtogroup std_random_generators Random Number Generators
-   * @ingroup std_random
+   * @addtogroup random_generators Random Number Generators
+   * @ingroup random
    *
    * These classes define objects which provide random or pseudorandom
    * numbers, either from a discrete or a continuous interval.  The
@@ -160,8 +225,11 @@ namespace std
   /**
    * @brief A model of a linear congruential random number generator.
    *
-   * A random number generator that produces pseudorandom numbers using the
-   * linear function @f$x_{i+1}\leftarrow(ax_{i} + c) \bmod m @f$.
+   * A random number generator that produces pseudorandom numbers via
+   * linear function:
+   * @f[
+   *     x_{i+1}\leftarrow(ax_{i} + c) \bmod m 
+   * @f]
    *
    * The template parameter @p _UIntType must be an unsigned integral type
    * large enough to store values up to (__m-1). If the template parameter
@@ -169,27 +237,27 @@ namespace std
    * std::numeric_limits<_UIntType>::max() plus 1. Otherwise, the template
    * parameters @p __a and @p __c must be less than @p __m.
    *
-   * The size of the state is @f$ 1 @f$.
+   * The size of the state is @f$1@f$.
    */
   template<typename _UIntType, _UIntType __a, _UIntType __c, _UIntType __m>
     class linear_congruential_engine
     {
-      __glibcxx_class_requires(_UIntType, _UnsignedIntegerConcept)
-      static_assert(__m == 0 || (__a < __m && __c < __m),
-                   "template arguments out of bounds"
-                   " in linear_congruential_engine");
+      static_assert(std::is_unsigned<_UIntType>::value, "template argument "
+                   "substituting _UIntType not an unsigned integral type");
+      static_assert(__m == 0u || (__a < __m && __c < __m),
+                   "template argument substituting __m out of bounds");
 
     public:
       /** The type of the generated random value. */
       typedef _UIntType result_type;
 
       /** The multiplier. */
-      static const result_type multiplier   = __a;
+      static constexpr result_type multiplier   = __a;
       /** An increment. */
-      static const result_type increment    = __c;
+      static constexpr result_type increment    = __c;
       /** The modulus. */
-      static const result_type modulus      = __m;
-      static const result_type default_seed = 1u;
+      static constexpr result_type modulus      = __m;
+      static constexpr result_type default_seed = 1u;
 
       /**
        * @brief Constructs a %linear_congruential_engine random number
@@ -200,7 +268,7 @@ namespace std
        */
       explicit
       linear_congruential_engine(result_type __s = default_seed)
-      { this->seed(__s); }
+      { seed(__s); }
 
       /**
        * @brief Constructs a %linear_congruential_engine random number
@@ -208,9 +276,12 @@ namespace std
        *
        * @param __q the seed sequence.
        */
-      explicit
-      linear_congruential_engine(seed_seq& __q)
-      { this->seed(__q); }
+      template<typename _Sseq, typename = typename
+       std::enable_if<!std::is_same<_Sseq, linear_congruential_engine>::value>
+              ::type>
+        explicit
+        linear_congruential_engine(_Sseq& __q)
+        { seed(__q); }
 
       /**
        * @brief Reseeds the %linear_congruential_engine random number generator
@@ -228,34 +299,29 @@ namespace std
        *
        * @param __q the seed sequence.
        */
-      void
-      seed(seed_seq& __q);
+      template<typename _Sseq>
+        typename std::enable_if<std::is_class<_Sseq>::value>::type
+        seed(_Sseq& __q);
 
       /**
        * @brief Gets the smallest possible value in the output range.
        *
        * The minimum depends on the @p __c parameter: if it is zero, the
        * minimum generated must be > 0, otherwise 0 is allowed.
-       *
-       * @todo This should be constexpr.
        */
-      result_type
-      min() const
+      static constexpr result_type
+      min()
       { return __c == 0u ? 1u : 0u; }
 
       /**
        * @brief Gets the largest possible value in the output range.
-       *
-       * @todo This should be constexpr.
        */
-      result_type
-      max() const
+      static constexpr result_type
+      max()
       { return __m - 1u; }
 
       /**
        * @brief Discard a sequence of random numbers.
-       *
-       * @todo Look for a faster way to do discard.
        */
       void
       discard(unsigned long long __z)
@@ -270,7 +336,7 @@ namespace std
       result_type
       operator()()
       {
-       _M_x = __detail::__mod<_UIntType, __a, __c, __m>(_M_x);
+       _M_x = __detail::__mod<_UIntType, __m, __a, __c>(_M_x);
        return _M_x;
       }
 
@@ -282,7 +348,8 @@ namespace std
        * @param __rhs Another linear congruential random number generator
        *              object.
        *
-       * @returns true if the two objects are equal, false otherwise.
+       * @returns true if the infinite sequences of generated values
+       *          would be equal, false otherwise.
        */
       friend bool
       operator==(const linear_congruential_engine& __lhs,
@@ -298,12 +365,11 @@ namespace std
        * @returns __os.
        */
       template<typename _UIntType1, _UIntType1 __a1, _UIntType1 __c1,
-              _UIntType1 __m1,
-              typename _CharT, typename _Traits>
+              _UIntType1 __m1, typename _CharT, typename _Traits>
        friend std::basic_ostream<_CharT, _Traits>&
-       operator<<(std::basic_ostream<_CharT, _Traits>&,
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
                   const std::linear_congruential_engine<_UIntType1,
-                  __a1, __c1, __m1>&);
+                  __a1, __c1, __m1>& __lcr);
 
       /**
        * @brief Sets the state of the engine by reading its textual
@@ -319,17 +385,35 @@ namespace std
        * @returns __is.
        */
       template<typename _UIntType1, _UIntType1 __a1, _UIntType1 __c1,
-              _UIntType1 __m1,
-              typename _CharT, typename _Traits>
+              _UIntType1 __m1, typename _CharT, typename _Traits>
        friend std::basic_istream<_CharT, _Traits>&
-       operator>>(std::basic_istream<_CharT, _Traits>&,
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
                   std::linear_congruential_engine<_UIntType1, __a1,
-                  __c1, __m1>&);
+                  __c1, __m1>& __lcr);
 
     private:
       _UIntType _M_x;
     };
 
+  /**
+   * @brief Compares two linear congruential random number generator
+   * objects of the same type for inequality.
+   *
+   * @param __lhs A linear congruential random number generator object.
+   * @param __rhs Another linear congruential random number generator
+   *              object.
+   *
+   * @returns true if the infinite sequences of generated values
+   *          would be different, false otherwise.
+   */
+  template<typename _UIntType, _UIntType __a, _UIntType __c, _UIntType __m>
+    inline bool
+    operator!=(const std::linear_congruential_engine<_UIntType, __a,
+              __c, __m>& __lhs,
+              const std::linear_congruential_engine<_UIntType, __a,
+              __c, __m>& __rhs)
+    { return !(__lhs == __rhs); }
+
 
   /**
    * A generalized feedback shift register discrete random number generator.
@@ -344,17 +428,20 @@ namespace std
    * This algorithm was originally invented by Makoto Matsumoto and
    * Takuji Nishimura.
    *
-   * @var word_size   The number of bits in each element of the state vector.
-   * @var state_size  The degree of recursion.
-   * @var shift_size  The period parameter.
-   * @var mask_bits   The separation point bit index.
-   * @var parameter_a The last row of the twist matrix.
-   * @var output_u    The first right-shift tempering matrix parameter.
-   * @var output_s    The first left-shift tempering matrix parameter.
-   * @var output_b    The first left-shift tempering matrix mask.
-   * @var output_t    The second left-shift tempering matrix parameter.
-   * @var output_c    The second left-shift tempering matrix mask.
-   * @var output_l    The second right-shift tempering matrix parameter.
+   * @tparam __w  Word size, the number of bits in each element of 
+   *              the state vector.
+   * @tparam __n  The degree of recursion.
+   * @tparam __m  The period parameter.
+   * @tparam __r  The separation point bit index.
+   * @tparam __a  The last row of the twist matrix.
+   * @tparam __u  The first right-shift tempering matrix parameter.
+   * @tparam __d  The first right-shift tempering matrix mask.
+   * @tparam __s  The first left-shift tempering matrix parameter.
+   * @tparam __b  The first left-shift tempering matrix mask.
+   * @tparam __t  The second left-shift tempering matrix parameter.
+   * @tparam __c  The second left-shift tempering matrix mask.
+   * @tparam __l  The second right-shift tempering matrix parameter.
+   * @tparam __f  Initialization multiplier.
    */
   template<typename _UIntType, size_t __w,
           size_t __n, size_t __m, size_t __r,
@@ -363,51 +450,52 @@ namespace std
           _UIntType __c, size_t __l, _UIntType __f>
     class mersenne_twister_engine
     {
-      __glibcxx_class_requires(_UIntType, _UnsignedIntegerConcept)
-
-      static_assert(__m >= 1U, 
-                   "mersenne_twister_engine template arguments out of bounds");
-      static_assert(__n >= __m,
-                   "mersenne_twister_engine template arguments out of bounds");
-      static_assert(__w >= __r,
-                   "mersenne_twister_engine template arguments out of bounds");
-      static_assert(__w >= __u,
-                   "mersenne_twister_engine template arguments out of bounds");
-      static_assert(__w >= __s,
-                   "mersenne_twister_engine template arguments out of bounds");
-      static_assert(__w >= __t,
-                   "mersenne_twister_engine template arguments out of bounds");
-      static_assert(__w >= __l,
-                   "mersenne_twister_engine template arguments out of bounds");
-      static_assert(__w <=
-                   static_cast<size_t>(numeric_limits<_UIntType>::digits),
-                   "mersenne_twister_engine template arguments out of bounds");
+      static_assert(std::is_unsigned<_UIntType>::value, "template argument "
+                   "substituting _UIntType not an unsigned integral type");
+      static_assert(1u <= __m && __m <= __n,
+                   "template argument substituting __m out of bounds");
+      static_assert(__r <= __w, "template argument substituting "
+                   "__r out of bound");
+      static_assert(__u <= __w, "template argument substituting "
+                   "__u out of bound");
+      static_assert(__s <= __w, "template argument substituting "
+                   "__s out of bound");
+      static_assert(__t <= __w, "template argument substituting "
+                   "__t out of bound");
+      static_assert(__l <= __w, "template argument substituting "
+                   "__l out of bound");
+      static_assert(__w <= std::numeric_limits<_UIntType>::digits,
+                   "template argument substituting __w out of bound");
       static_assert(__a <= (__detail::_Shift<_UIntType, __w>::__value - 1),
-                   "mersenne_twister_engine template arguments out of bounds");
+                   "template argument substituting __a out of bound");
       static_assert(__b <= (__detail::_Shift<_UIntType, __w>::__value - 1),
-                   "mersenne_twister_engine template arguments out of bounds");
+                   "template argument substituting __b out of bound");
       static_assert(__c <= (__detail::_Shift<_UIntType, __w>::__value - 1),
-                   "mersenne_twister_engine template arguments out of bounds");
+                   "template argument substituting __c out of bound");
+      static_assert(__d <= (__detail::_Shift<_UIntType, __w>::__value - 1),
+                   "template argument substituting __d out of bound");
+      static_assert(__f <= (__detail::_Shift<_UIntType, __w>::__value - 1),
+                   "template argument substituting __f out of bound");
 
     public:
       /** The type of the generated random value. */
       typedef _UIntType result_type;
 
       // parameter values
-      static const size_t      word_size                 = __w;
-      static const size_t      state_size                = __n;
-      static const size_t      shift_size                = __m;
-      static const size_t      mask_bits                 = __r;
-      static const result_type xor_mask                  = __a;
-      static const size_t      tempering_u               = __u;
-      static const result_type tempering_d               = __d;
-      static const size_t      tempering_s               = __s;
-      static const result_type tempering_b               = __b;
-      static const size_t      tempering_t               = __t;
-      static const result_type tempering_c               = __c;
-      static const size_t      tempering_l               = __l;
-      static const size_t      initialization_multiplier = __f;
-      static const result_type default_seed = 5489u;
+      static constexpr size_t      word_size                 = __w;
+      static constexpr size_t      state_size                = __n;
+      static constexpr size_t      shift_size                = __m;
+      static constexpr size_t      mask_bits                 = __r;
+      static constexpr result_type xor_mask                  = __a;
+      static constexpr size_t      tempering_u               = __u;
+      static constexpr result_type tempering_d               = __d;
+      static constexpr size_t      tempering_s               = __s;
+      static constexpr result_type tempering_b               = __b;
+      static constexpr size_t      tempering_t               = __t;
+      static constexpr result_type tempering_c               = __c;
+      static constexpr size_t      tempering_l               = __l;
+      static constexpr result_type initialization_multiplier = __f;
+      static constexpr result_type default_seed = 5489u;
 
       // constructors and member function
       explicit
@@ -420,45 +508,39 @@ namespace std
        *
        * @param __q the seed sequence.
        */
-      explicit
-      mersenne_twister_engine(seed_seq& __q)
-      { seed(__q); }
+      template<typename _Sseq, typename = typename
+        std::enable_if<!std::is_same<_Sseq, mersenne_twister_engine>::value>
+              ::type>
+        explicit
+        mersenne_twister_engine(_Sseq& __q)
+        { seed(__q); }
 
       void
       seed(result_type __sd = default_seed);
 
-      void
-      seed(seed_seq& __q);
+      template<typename _Sseq>
+       typename std::enable_if<std::is_class<_Sseq>::value>::type
+        seed(_Sseq& __q);
 
       /**
        * @brief Gets the smallest possible value in the output range.
-       *
-       * @todo This should be constexpr.
        */
-      result_type
-      min() const
+      static constexpr result_type
+      min()
       { return 0; };
 
       /**
        * @brief Gets the largest possible value in the output range.
-       *
-       * @todo This should be constexpr.
        */
-      result_type
-      max() const
+      static constexpr result_type
+      max()
       { return __detail::_Shift<_UIntType, __w>::__value - 1; }
 
       /**
        * @brief Discard a sequence of random numbers.
-       *
-       * @todo Look for a faster way to do discard.
        */
       void
-      discard(unsigned long long __z)
-      {
-       for (; __z != 0ULL; --__z)
-         (*this)();
-      }
+      discard(unsigned long long __z);
 
       result_type
       operator()();
@@ -472,12 +554,14 @@ namespace std
        * @param __rhs Another % mersenne_twister_engine random number
        *              generator object.
        *
-       * @returns true if the two objects are equal, false otherwise.
+       * @returns true if the infinite sequences of generated values
+       *          would be equal, false otherwise.
        */
       friend bool
       operator==(const mersenne_twister_engine& __lhs,
                 const mersenne_twister_engine& __rhs)
-      { return std::equal(__lhs._M_x, __lhs._M_x + state_size, __rhs._M_x); }
+      { return (std::equal(__lhs._M_x, __lhs._M_x + state_size, __rhs._M_x)
+               && __lhs._M_p == __rhs._M_p); }
 
       /**
        * @brief Inserts the current state of a % mersenne_twister_engine
@@ -500,10 +584,10 @@ namespace std
               _UIntType1 __c1, size_t __l1, _UIntType1 __f1,
               typename _CharT, typename _Traits>
        friend std::basic_ostream<_CharT, _Traits>&
-       operator<<(std::basic_ostream<_CharT, _Traits>&,
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
                   const std::mersenne_twister_engine<_UIntType1, __w1, __n1,
                   __m1, __r1, __a1, __u1, __d1, __s1, __b1, __t1, __c1,
-                  __l1, __f1>&);
+                  __l1, __f1>& __x);
 
       /**
        * @brief Extracts the current state of a % mersenne_twister_engine
@@ -526,16 +610,43 @@ namespace std
               _UIntType1 __c1, size_t __l1, _UIntType1 __f1,
               typename _CharT, typename _Traits>
        friend std::basic_istream<_CharT, _Traits>&
-       operator>>(std::basic_istream<_CharT, _Traits>&,
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
                   std::mersenne_twister_engine<_UIntType1, __w1, __n1, __m1,
                   __r1, __a1, __u1, __d1, __s1, __b1, __t1, __c1,
-                  __l1, __f1>&);
+                  __l1, __f1>& __x);
 
     private:
+      void _M_gen_rand();
+
       _UIntType _M_x[state_size];
       size_t    _M_p;
     };
 
+  /**
+   * @brief Compares two % mersenne_twister_engine random number generator
+   *        objects of the same type for inequality.
+   *
+   * @param __lhs A % mersenne_twister_engine random number generator
+   *              object.
+   * @param __rhs Another % mersenne_twister_engine random number
+   *              generator object.
+   *
+   * @returns true if the infinite sequences of generated values
+   *          would be different, false otherwise.
+   */
+  template<typename _UIntType, size_t __w,
+          size_t __n, size_t __m, size_t __r,
+          _UIntType __a, size_t __u, _UIntType __d, size_t __s,
+          _UIntType __b, size_t __t,
+          _UIntType __c, size_t __l, _UIntType __f>
+    inline bool
+    operator!=(const std::mersenne_twister_engine<_UIntType, __w, __n, __m,
+              __r, __a, __u, __d, __s, __b, __t, __c, __l, __f>& __lhs,
+              const std::mersenne_twister_engine<_UIntType, __w, __n, __m,
+              __r, __a, __u, __d, __s, __b, __t, __c, __l, __f>& __rhs)
+    { return !(__lhs == __rhs); }
+
+
   /**
    * @brief The Marsaglia-Zaman generator.
    *
@@ -543,35 +654,33 @@ namespace std
    * generator, sometimes referred to as the SWC generator.
    *
    * A discrete random number generator that produces pseudorandom
-   * numbers using @f$x_{i}\leftarrow(x_{i - s} - x_{i - r} -
-   * carry_{i-1}) \bmod m @f$.
-   *
-   * The size of the state is @f$ r @f$
-   * and the maximum period of the generator is @f$ m^r - m^s - 1 @f$.
+   * numbers using:
+   * @f[
+   *     x_{i}\leftarrow(x_{i - s} - x_{i - r} - carry_{i-1}) \bmod m 
+   * @f]
    *
-   * @var _M_x     The state of the generator.  This is a ring buffer.
-   * @var _M_carry The carry.
-   * @var _M_p     Current index of x(i - r).
+   * The size of the state is @f$r@f$
+   * and the maximum period of the generator is @f$(m^r - m^s - 1)@f$.
    */
   template<typename _UIntType, size_t __w, size_t __s, size_t __r>
     class subtract_with_carry_engine
     {
-      __glibcxx_class_requires(_UIntType, _UnsignedIntegerConcept)
-      static_assert(__s > 0U && __r > __s
-                && __w > 0U
-                && __w <= static_cast<size_t>(numeric_limits<_UIntType>::digits),
-                   "template arguments out of bounds"
-                   " in subtract_with_carry_engine");
+      static_assert(std::is_unsigned<_UIntType>::value, "template argument "
+                   "substituting _UIntType not an unsigned integral type");
+      static_assert(0u < __s && __s < __r,
+                   "template argument substituting __s out of bounds");
+      static_assert(0u < __w && __w <= std::numeric_limits<_UIntType>::digits,
+                   "template argument substituting __w out of bounds");
 
     public:
       /** The type of the generated random value. */
       typedef _UIntType result_type;
 
       // parameter values
-      static const size_t      word_size    = __w;
-      static const size_t      short_lag    = __s;
-      static const size_t      long_lag     = __r;
-      static const result_type default_seed = 19780503u;
+      static constexpr size_t      word_size    = __w;
+      static constexpr size_t      short_lag    = __s;
+      static constexpr size_t      long_lag     = __r;
+      static constexpr result_type default_seed = 19780503u;
 
       /**
        * @brief Constructs an explicitly seeded % subtract_with_carry_engine
@@ -579,7 +688,7 @@ namespace std
        */
       explicit
       subtract_with_carry_engine(result_type __sd = default_seed)
-      { this->seed(__sd); }
+      { seed(__sd); }
 
       /**
        * @brief Constructs a %subtract_with_carry_engine random number engine
@@ -587,12 +696,15 @@ namespace std
        *
        * @param __q the seed sequence.
        */
-      explicit
-      subtract_with_carry_engine(seed_seq& __q)
-      { this->seed(__q); }
+      template<typename _Sseq, typename = typename
+        std::enable_if<!std::is_same<_Sseq, subtract_with_carry_engine>::value>
+              ::type>
+        explicit
+        subtract_with_carry_engine(_Sseq& __q)
+        { seed(__q); }
 
       /**
-       * @brief Seeds the initial state @f$ x_0 @f$ of the random number
+       * @brief Seeds the initial state @f$x_0@f$ of the random number
        *        generator.
        *
        * N1688[4.19] modifies this as follows.  If @p __value == 0,
@@ -607,36 +719,31 @@ namespace std
       seed(result_type __sd = default_seed);
 
       /**
-       * @brief Seeds the initial state @f$ x_0 @f$ of the
+       * @brief Seeds the initial state @f$x_0@f$ of the
        * % subtract_with_carry_engine random number generator.
        */
-      void
-      seed(seed_seq& __q);
+      template<typename _Sseq>
+       typename std::enable_if<std::is_class<_Sseq>::value>::type
+        seed(_Sseq& __q);
 
       /**
        * @brief Gets the inclusive minimum value of the range of random
        * integers returned by this generator.
-       *
-       * @todo This should be constexpr.
        */
-      result_type
-      min() const
+      static constexpr result_type
+      min()
       { return 0; }
 
       /**
        * @brief Gets the inclusive maximum value of the range of random
        * integers returned by this generator.
-       *
-       * @todo This should be constexpr.
        */
-      result_type
-      max() const
+      static constexpr result_type
+      max()
       { return __detail::_Shift<_UIntType, __w>::__value - 1; }
 
       /**
        * @brief Discard a sequence of random numbers.
-       *
-       * @todo Look for a faster way to do discard.
        */
       void
       discard(unsigned long long __z)
@@ -660,12 +767,15 @@ namespace std
        * @param __rhs Another % subtract_with_carry_engine random number
        *              generator object.
        *
-       * @returns true if the two objects are equal, false otherwise.
-       */
+       * @returns true if the infinite sequences of generated values
+       *          would be equal, false otherwise.
+      */
       friend bool
       operator==(const subtract_with_carry_engine& __lhs,
                 const subtract_with_carry_engine& __rhs)
-      { return std::equal(__lhs._M_x, __lhs._M_x + long_lag, __rhs._M_x); }
+      { return (std::equal(__lhs._M_x, __lhs._M_x + long_lag, __rhs._M_x)
+               && __lhs._M_carry == __rhs._M_carry
+               && __lhs._M_p == __rhs._M_p); }
 
       /**
        * @brief Inserts the current state of a % subtract_with_carry_engine
@@ -682,9 +792,9 @@ namespace std
       template<typename _UIntType1, size_t __w1, size_t __s1, size_t __r1,
               typename _CharT, typename _Traits>
        friend std::basic_ostream<_CharT, _Traits>&
-       operator<<(std::basic_ostream<_CharT, _Traits>&,
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
                   const std::subtract_with_carry_engine<_UIntType1, __w1,
-                  __s1, __r1>&);
+                  __s1, __r1>& __x);
 
       /**
        * @brief Extracts the current state of a % subtract_with_carry_engine
@@ -692,7 +802,8 @@ namespace std
        *        @p __is.
        *
        * @param __is An input stream.
-       * @param __x  A % subtract_with_carry_engine random number generator engine.
+       * @param __x  A % subtract_with_carry_engine random number generator
+       *             engine.
        *
        * @returns The input stream with the state of @p __x extracted or in
        * an error state.
@@ -700,16 +811,38 @@ namespace std
       template<typename _UIntType1, size_t __w1, size_t __s1, size_t __r1,
               typename _CharT, typename _Traits>
        friend std::basic_istream<_CharT, _Traits>&
-       operator>>(std::basic_istream<_CharT, _Traits>&,
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
                   std::subtract_with_carry_engine<_UIntType1, __w1,
-                  __s1, __r1>&);
+                  __s1, __r1>& __x);
 
     private:
+      /// The state of the generator.  This is a ring buffer.
       _UIntType  _M_x[long_lag];
-      _UIntType  _M_carry;
-      size_t     _M_p;
+      _UIntType  _M_carry;             ///< The carry
+      size_t     _M_p;                 ///< Current index of x(i - r).
     };
 
+  /**
+   * @brief Compares two % subtract_with_carry_engine random number
+   *        generator objects of the same type for inequality.
+   *
+   * @param __lhs A % subtract_with_carry_engine random number generator
+   *              object.
+   * @param __rhs Another % subtract_with_carry_engine random number
+   *              generator object.
+   *
+   * @returns true if the infinite sequences of generated values
+   *          would be different, false otherwise.
+   */
+  template<typename _UIntType, size_t __w, size_t __s, size_t __r>
+    inline bool
+    operator!=(const std::subtract_with_carry_engine<_UIntType, __w,
+              __s, __r>& __lhs,
+              const std::subtract_with_carry_engine<_UIntType, __w,
+              __s, __r>& __rhs)
+    { return !(__lhs == __rhs); }
+
+
   /**
    * Produces random numbers from some base engine by discarding blocks of
    * data.
@@ -719,17 +852,16 @@ namespace std
   template<typename _RandomNumberEngine, size_t __p, size_t __r>
     class discard_block_engine
     {
-      static_assert(__r >= 1U && __p >= __r,
-                   "template arguments out of bounds"
-                   " in discard_block_engine");
+      static_assert(1 <= __r && __r <= __p,
+                   "template argument substituting __r out of bounds");
 
     public:
       /** The type of the generated random value. */
       typedef typename _RandomNumberEngine::result_type result_type;
 
       // parameter values
-      static const size_t block_size = __p;
-      static const size_t used_block = __r;
+      static constexpr size_t block_size = __p;
+      static constexpr size_t used_block = __r;
 
       /**
        * @brief Constructs a default %discard_block_engine engine.
@@ -743,21 +875,21 @@ namespace std
        * @brief Copy constructs a %discard_block_engine engine.
        *
        * Copies an existing base class random number generator.
-       * @param rng An existing (base class) engine object.
+       * @param __rng An existing (base class) engine object.
        */
       explicit
-      discard_block_engine(const _RandomNumberEngine& __rne)
-      : _M_b(__rne), _M_n(0) { }
+      discard_block_engine(const _RandomNumberEngine& __rng)
+      : _M_b(__rng), _M_n(0) { }
 
       /**
        * @brief Move constructs a %discard_block_engine engine.
        *
        * Copies an existing base class random number generator.
-       * @param rng An existing (base class) engine object.
+       * @param __rng An existing (base class) engine object.
        */
       explicit
-      discard_block_engine(_RandomNumberEngine&& __rne)
-      : _M_b(std::move(__rne)), _M_n(0) { }
+      discard_block_engine(_RandomNumberEngine&& __rng)
+      : _M_b(std::move(__rng)), _M_n(0) { }
 
       /**
        * @brief Seed constructs a %discard_block_engine engine.
@@ -774,10 +906,14 @@ namespace std
        *
        * @param __q A seed sequence.
        */
-      explicit
-      discard_block_engine(seed_seq& __q)
-      : _M_b(__q), _M_n(0)
-      { }
+      template<typename _Sseq, typename = typename
+       std::enable_if<!std::is_same<_Sseq, discard_block_engine>::value
+                      && !std::is_same<_Sseq, _RandomNumberEngine>::value>
+              ::type>
+        explicit
+        discard_block_engine(_Sseq& __q)
+       : _M_b(__q), _M_n(0)
+        { }
 
       /**
        * @brief Reseeds the %discard_block_engine object with the default
@@ -806,43 +942,38 @@ namespace std
        *        sequence.
        * @param __q A seed generator function.
        */
-      void
-      seed(seed_seq& __q)
-      {
-        _M_b.seed(__q);
-        _M_n = 0;
-      }
+      template<typename _Sseq>
+        void
+        seed(_Sseq& __q)
+        {
+         _M_b.seed(__q);
+         _M_n = 0;
+       }
 
       /**
        * @brief Gets a const reference to the underlying generator engine
        *        object.
        */
       const _RandomNumberEngine&
-      base() const
+      base() const noexcept
       { return _M_b; }
 
       /**
        * @brief Gets the minimum value in the generated random number range.
-       *
-       * @todo This should be constexpr.
        */
-      result_type
-      min() const
-      { return _M_b.min(); }
+      static constexpr result_type
+      min()
+      { return _RandomNumberEngine::min(); }
 
       /**
        * @brief Gets the maximum value in the generated random number range.
-       *
-       * @todo This should be constexpr.
        */
-      result_type
-      max() const
-      { return _M_b.max(); }
+      static constexpr result_type
+      max()
+      { return _RandomNumberEngine::max(); }
 
       /**
        * @brief Discard a sequence of random numbers.
-       *
-       * @todo Look for a faster way to do discard.
        */
       void
       discard(unsigned long long __z)
@@ -865,12 +996,13 @@ namespace std
        * @param __rhs Another %discard_block_engine random number generator
        *              object.
        *
-       * @returns true if the two objects are equal, false otherwise.
+       * @returns true if the infinite sequences of generated values
+       *          would be equal, false otherwise.
        */
       friend bool
       operator==(const discard_block_engine& __lhs,
                 const discard_block_engine& __rhs)
-      { return (__lhs._M_b == __rhs._M_b) && (__lhs._M_n == __rhs._M_n); }
+      { return __lhs._M_b == __rhs._M_b && __lhs._M_n == __rhs._M_n; }
 
       /**
        * @brief Inserts the current state of a %discard_block_engine random
@@ -886,9 +1018,9 @@ namespace std
       template<typename _RandomNumberEngine1, size_t __p1, size_t __r1,
               typename _CharT, typename _Traits>
        friend std::basic_ostream<_CharT, _Traits>&
-       operator<<(std::basic_ostream<_CharT, _Traits>&,
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
                   const std::discard_block_engine<_RandomNumberEngine1,
-                  __p1, __r1>&);
+                  __p1, __r1>& __x);
 
       /**
        * @brief Extracts the current state of a % subtract_with_carry_engine
@@ -904,15 +1036,35 @@ namespace std
       template<typename _RandomNumberEngine1, size_t __p1, size_t __r1,
               typename _CharT, typename _Traits>
        friend std::basic_istream<_CharT, _Traits>&
-       operator>>(std::basic_istream<_CharT, _Traits>&,
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
                   std::discard_block_engine<_RandomNumberEngine1,
-                  __p1, __r1>&);
+                  __p1, __r1>& __x);
 
     private:
       _RandomNumberEngine _M_b;
       size_t _M_n;
     };
 
+  /**
+   * @brief Compares two %discard_block_engine random number generator
+   *        objects of the same type for inequality.
+   *
+   * @param __lhs A %discard_block_engine random number generator object.
+   * @param __rhs Another %discard_block_engine random number generator
+   *              object.
+   *
+   * @returns true if the infinite sequences of generated values
+   *          would be different, false otherwise.
+   */
+  template<typename _RandomNumberEngine, size_t __p, size_t __r>
+    inline bool
+    operator!=(const std::discard_block_engine<_RandomNumberEngine, __p,
+              __r>& __lhs,
+              const std::discard_block_engine<_RandomNumberEngine, __p,
+              __r>& __rhs)
+    { return !(__lhs == __rhs); }
+
+
   /**
    * Produces random numbers by combining random numbers from some base
    * engine to produce random numbers with a specifies number of bits @p __w.
@@ -920,11 +1072,10 @@ namespace std
   template<typename _RandomNumberEngine, size_t __w, typename _UIntType>
     class independent_bits_engine
     {
-      static_assert(__w > 0U
-                   && __w <=
-                   static_cast<size_t>(numeric_limits<_UIntType>::digits),
-                   "template arguments out of bounds "
-                   "in independent_bits_engine");
+      static_assert(std::is_unsigned<_UIntType>::value, "template argument "
+                   "substituting _UIntType not an unsigned integral type");
+      static_assert(0u < __w && __w <= std::numeric_limits<_UIntType>::digits,
+                   "template argument substituting __w out of bounds");
 
     public:
       /** The type of the generated random value. */
@@ -942,21 +1093,21 @@ namespace std
        * @brief Copy constructs a %independent_bits_engine engine.
        *
        * Copies an existing base class random number generator.
-       * @param rng An existing (base class) engine object.
+       * @param __rng An existing (base class) engine object.
        */
       explicit
-      independent_bits_engine(const _RandomNumberEngine& __rne)
-      : _M_b(__rne) { }
+      independent_bits_engine(const _RandomNumberEngine& __rng)
+      : _M_b(__rng) { }
 
       /**
        * @brief Move constructs a %independent_bits_engine engine.
        *
        * Copies an existing base class random number generator.
-       * @param rng An existing (base class) engine object.
+       * @param __rng An existing (base class) engine object.
        */
       explicit
-      independent_bits_engine(_RandomNumberEngine&& __rne)
-      : _M_b(std::move(__rne)) { }
+      independent_bits_engine(_RandomNumberEngine&& __rng)
+      : _M_b(std::move(__rng)) { }
 
       /**
        * @brief Seed constructs a %independent_bits_engine engine.
@@ -973,10 +1124,14 @@ namespace std
        *
        * @param __q A seed sequence.
        */
-      explicit
-      independent_bits_engine(seed_seq& __q)
-      : _M_b(__q)
-      { }
+      template<typename _Sseq, typename = typename
+       std::enable_if<!std::is_same<_Sseq, independent_bits_engine>::value
+                      && !std::is_same<_Sseq, _RandomNumberEngine>::value>
+               ::type>
+        explicit
+        independent_bits_engine(_Sseq& __q)
+        : _M_b(__q)
+        { }
 
       /**
        * @brief Reseeds the %independent_bits_engine object with the default
@@ -999,40 +1154,35 @@ namespace std
        *        seed sequence.
        * @param __q A seed generator function.
        */
-      void
-      seed(seed_seq& __q)
-      { _M_b.seed(__q); }
+      template<typename _Sseq>
+        void
+        seed(_Sseq& __q)
+        { _M_b.seed(__q); }
 
       /**
        * @brief Gets a const reference to the underlying generator engine
        *        object.
        */
       const _RandomNumberEngine&
-      base() const
+      base() const noexcept
       { return _M_b; }
 
       /**
        * @brief Gets the minimum value in the generated random number range.
-       *
-       * @todo This should be constexpr.
        */
-      result_type
-      min() const
+      static constexpr result_type
+      min()
       { return 0U; }
 
       /**
        * @brief Gets the maximum value in the generated random number range.
-       *
-       * @todo This should be constexpr.
        */
-      result_type
-      max() const
+      static constexpr result_type
+      max()
       { return __detail::_Shift<_UIntType, __w>::__value - 1; }
 
       /**
        * @brief Discard a sequence of random numbers.
-       *
-       * @todo Look for a faster way to do discard.
        */
       void
       discard(unsigned long long __z)
@@ -1056,7 +1206,8 @@ namespace std
        * @param __rhs Another %independent_bits_engine random number generator
        *              object.
        *
-       * @returns true if the two objects are equal, false otherwise.
+       * @returns true if the infinite sequences of generated values
+       *          would be equal, false otherwise.
        */
       friend bool
       operator==(const independent_bits_engine& __lhs,
@@ -1089,6 +1240,26 @@ namespace std
       _RandomNumberEngine _M_b;
     };
 
+  /**
+   * @brief Compares two %independent_bits_engine random number generator
+   * objects of the same type for inequality.
+   *
+   * @param __lhs A %independent_bits_engine random number generator
+   *              object.
+   * @param __rhs Another %independent_bits_engine random number generator
+   *              object.
+   *
+   * @returns true if the infinite sequences of generated values
+   *          would be different, false otherwise.
+   */
+  template<typename _RandomNumberEngine, size_t __w, typename _UIntType>
+    inline bool
+    operator!=(const std::independent_bits_engine<_RandomNumberEngine, __w,
+              _UIntType>& __lhs,
+              const std::independent_bits_engine<_RandomNumberEngine, __w,
+              _UIntType>& __rhs)
+    { return !(__lhs == __rhs); }
+
   /**
    * @brief Inserts the current state of a %independent_bits_engine random
    *        number generator engine @p __x into the output stream @p __os.
@@ -1110,6 +1281,7 @@ namespace std
       return __os;
     }
 
+
   /**
    * @brief Produces random numbers by combining random numbers from some
    * base engine to produce random numbers with a specifies number of bits
@@ -1118,15 +1290,14 @@ namespace std
   template<typename _RandomNumberEngine, size_t __k>
     class shuffle_order_engine
     {
-      static_assert(__k >= 1U,
-                   "template arguments out of bounds"
-                   " in shuffle_order_engine");
+      static_assert(1u <= __k, "template argument substituting "
+                   "__k out of bound");
 
     public:
       /** The type of the generated random value. */
       typedef typename _RandomNumberEngine::result_type result_type;
 
-      static const size_t table_size = __k;
+      static constexpr size_t table_size = __k;
 
       /**
        * @brief Constructs a default %shuffle_order_engine engine.
@@ -1141,22 +1312,22 @@ namespace std
        * @brief Copy constructs a %shuffle_order_engine engine.
        *
        * Copies an existing base class random number generator.
-       * @param rng An existing (base class) engine object.
+       * @param __rng An existing (base class) engine object.
        */
       explicit
-      shuffle_order_engine(const _RandomNumberEngine& __rne)
-      : _M_b(__rne)
+      shuffle_order_engine(const _RandomNumberEngine& __rng)
+      : _M_b(__rng)
       { _M_initialize(); }
 
       /**
        * @brief Move constructs a %shuffle_order_engine engine.
        *
        * Copies an existing base class random number generator.
-       * @param rng An existing (base class) engine object.
+       * @param __rng An existing (base class) engine object.
        */
       explicit
-      shuffle_order_engine(_RandomNumberEngine&& __rne)
-      : _M_b(std::move(__rne))
+      shuffle_order_engine(_RandomNumberEngine&& __rng)
+      : _M_b(std::move(__rng))
       { _M_initialize(); }
 
       /**
@@ -1175,10 +1346,14 @@ namespace std
        *
        * @param __q A seed sequence.
        */
-      explicit
-      shuffle_order_engine(seed_seq& __q)
-      : _M_b(__q)
-      { _M_initialize(); }
+      template<typename _Sseq, typename = typename
+       std::enable_if<!std::is_same<_Sseq, shuffle_order_engine>::value
+                      && !std::is_same<_Sseq, _RandomNumberEngine>::value>
+              ::type>
+        explicit
+        shuffle_order_engine(_Sseq& __q)
+        : _M_b(__q)
+        { _M_initialize(); }
 
       /**
        * @brief Reseeds the %shuffle_order_engine object with the default seed
@@ -1207,42 +1382,37 @@ namespace std
        *        sequence.
        * @param __q A seed generator function.
        */
-      void
-      seed(seed_seq& __q)
-      {
-        _M_b.seed(__q);
-        _M_initialize();
-      }
+      template<typename _Sseq>
+        void
+        seed(_Sseq& __q)
+        {
+         _M_b.seed(__q);
+         _M_initialize();
+       }
 
       /**
        * Gets a const reference to the underlying generator engine object.
        */
       const _RandomNumberEngine&
-      base() const
+      base() const noexcept
       { return _M_b; }
 
       /**
        * Gets the minimum value in the generated random number range.
-       *
-       * @todo This should be constexpr.
        */
-      result_type
-      min() const
-      { return _M_b.min(); }
+      static constexpr result_type
+      min()
+      { return _RandomNumberEngine::min(); }
 
       /**
        * Gets the maximum value in the generated random number range.
-       *
-       * @todo This should be constexpr.
        */
-      result_type
-      max() const
-      { return _M_b.max(); }
+      static constexpr result_type
+      max()
+      { return _RandomNumberEngine::max(); }
 
       /**
        * Discard a sequence of random numbers.
-       *
-       * @todo Look for a faster way to do discard.
        */
       void
       discard(unsigned long long __z)
@@ -1265,12 +1435,15 @@ namespace std
        * @param __rhs Another %shuffle_order_engine random number generator
        *              object.
        *
-       * @returns true if the two objects are equal, false otherwise.
-       */
+       * @returns true if the infinite sequences of generated values
+       *          would be equal, false otherwise.
+      */
       friend bool
       operator==(const shuffle_order_engine& __lhs,
                 const shuffle_order_engine& __rhs)
-      { return __lhs._M_b == __rhs._M_b; }
+      { return (__lhs._M_b == __rhs._M_b
+               && std::equal(__lhs._M_v, __lhs._M_v + __k, __rhs._M_v)
+               && __lhs._M_y == __rhs._M_y); }
 
       /**
        * @brief Inserts the current state of a %shuffle_order_engine random
@@ -1286,9 +1459,9 @@ namespace std
       template<typename _RandomNumberEngine1, size_t __k1,
               typename _CharT, typename _Traits>
        friend std::basic_ostream<_CharT, _Traits>&
-       operator<<(std::basic_ostream<_CharT, _Traits>&,
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
                   const std::shuffle_order_engine<_RandomNumberEngine1,
-                  __k1>&);
+                  __k1>& __x);
 
       /**
        * @brief Extracts the current state of a % subtract_with_carry_engine
@@ -1304,8 +1477,8 @@ namespace std
       template<typename _RandomNumberEngine1, size_t __k1,
               typename _CharT, typename _Traits>
        friend std::basic_istream<_CharT, _Traits>&
-       operator>>(std::basic_istream<_CharT, _Traits>&,
-                  std::shuffle_order_engine<_RandomNumberEngine1, __k1>&);
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
+                  std::shuffle_order_engine<_RandomNumberEngine1, __k1>& __x);
 
     private:
       void _M_initialize()
@@ -1320,6 +1493,26 @@ namespace std
       result_type _M_y;
     };
 
+  /**
+   * Compares two %shuffle_order_engine random number generator objects
+   * of the same type for inequality.
+   *
+   * @param __lhs A %shuffle_order_engine random number generator object.
+   * @param __rhs Another %shuffle_order_engine random number generator
+   *              object.
+   *
+   * @returns true if the infinite sequences of generated values
+   *          would be different, false otherwise.
+   */
+  template<typename _RandomNumberEngine, size_t __k>
+    inline bool
+    operator!=(const std::shuffle_order_engine<_RandomNumberEngine,
+              __k>& __lhs,
+              const std::shuffle_order_engine<_RandomNumberEngine,
+              __k>& __rhs)
+    { return !(__lhs == __rhs); }
+
+
   /**
    * The classic Minimum Standard rand0 of Lewis, Goodman, and Miller.
    */
@@ -1327,7 +1520,7 @@ namespace std
   minstd_rand0;
 
   /**
-   * An alternative LCR (Lehmer Generator function) .
+   * An alternative LCR (Lehmer Generator function).
    */
   typedef linear_congruential_engine<uint_fast32_t, 48271UL, 0UL, 2147483647UL>
   minstd_rand;
@@ -1336,8 +1529,8 @@ namespace std
    * The classic Mersenne Twister.
    *
    * Reference:
-   * M. Matsumoto and T. Nishimura, "Mersenne Twister: A 623-Dimensionally
-   * Equidistributed Uniform Pseudo-Random Number Generator", ACM Transactions
+   * M. Matsumoto and T. Nishimura, Mersenne Twister: A 623-Dimensionally
+   * Equidistributed Uniform Pseudo-Random Number Generator, ACM Transactions
    * on Modeling and Computer Simulation, Vol. 8, No. 1, January 1998, pp 3-30.
    */
   typedef mersenne_twister_engine<
@@ -1360,27 +1553,18 @@ namespace std
     0xfff7eee000000000ULL, 43,
     6364136223846793005ULL> mt19937_64;
 
-  /**
-   * .
-   */
   typedef subtract_with_carry_engine<uint_fast32_t, 24, 10, 24>
     ranlux24_base;
 
-  typedef discard_block_engine<ranlux24_base, 223, 23> ranlux24;
-
   typedef subtract_with_carry_engine<uint_fast64_t, 48, 5, 12>
     ranlux48_base;
 
+  typedef discard_block_engine<ranlux24_base, 223, 23> ranlux24;
+
   typedef discard_block_engine<ranlux48_base, 389, 11> ranlux48;
 
-  /**
-   * .
-   */
   typedef shuffle_order_engine<minstd_rand0, 256> knuth_b;
 
-  /**
-   * .
-   */
   typedef minstd_rand0 default_random_engine;
 
   /**
@@ -1398,66 +1582,43 @@ namespace std
 #ifdef _GLIBCXX_USE_RANDOM_TR1
 
     explicit
-    random_device(const std::string& __token = "/dev/urandom")
+    random_device(const std::string& __token = "default")
     {
-      if ((__token != "/dev/urandom" && __token != "/dev/random")
-         || !(_M_file = std::fopen(__token.c_str(), "rb")))
-       std::__throw_runtime_error(__N("random_device::"
-                                      "random_device(const std::string&)"));
+      _M_init(__token);
     }
 
     ~random_device()
-    { std::fclose(_M_file); }
+    { _M_fini(); }
 
 #else
 
     explicit
     random_device(const std::string& __token = "mt19937")
-    : _M_mt(_M_strtoul(__token)) { }
-
-  private:
-    static unsigned long
-    _M_strtoul(const std::string& __str)
-    {
-      unsigned long __ret = 5489UL;
-      if (__str != "mt19937")
-       {
-         const char* __nptr = __str.c_str();
-         char* __endptr;
-         __ret = std::strtoul(__nptr, &__endptr, 0);
-         if (*__nptr == '\0' || *__endptr != '\0')
-           std::__throw_runtime_error(__N("random_device::_M_strtoul"
-                                          "(const std::string&)"));
-       }
-      return __ret;
-    }
+    { _M_init_pretr1(__token); }
 
   public:
 
 #endif
 
-    result_type
-    min() const
+    static constexpr result_type
+    min()
     { return std::numeric_limits<result_type>::min(); }
 
-    result_type
-    max() const
+    static constexpr result_type
+    max()
     { return std::numeric_limits<result_type>::max(); }
 
     double
-    entropy() const
+    entropy() const noexcept
     { return 0.0; }
 
     result_type
     operator()()
     {
 #ifdef _GLIBCXX_USE_RANDOM_TR1
-      result_type __ret;
-      std::fread(reinterpret_cast<void*>(&__ret), sizeof(result_type),
-                1, _M_file);
-      return __ret;
+      return this->_M_getval();
 #else
-      return _M_mt();
+      return this->_M_getval_pretr1();
 #endif
     }
 
@@ -1467,24 +1628,31 @@ namespace std
 
   private:
 
-#ifdef _GLIBCXX_USE_RANDOM_TR1
-    FILE*        _M_file;
-#else
-    mt19937      _M_mt;
-#endif
+    void _M_init(const std::string& __token);
+    void _M_init_pretr1(const std::string& __token);
+    void _M_fini();
+
+    result_type _M_getval();
+    result_type _M_getval_pretr1();
+
+    union
+    {
+      void*      _M_file;
+      mt19937    _M_mt;
+    };
   };
 
-  /* @} */ // group std_random_generators
+  /* @} */ // group random_generators
 
   /**
-   * @addtogroup std_random_distributions Random Number Distributions
-   * @ingroup std_random
+   * @addtogroup random_distributions Random Number Distributions
+   * @ingroup random
    * @{
    */
 
   /**
-   * @addtogroup std_random_distributions_uniform Uniform Distributions
-   * @ingroup std_random_distributions
+   * @addtogroup random_distributions_uniform Uniform Distributions
+   * @ingroup random_distributions
    * @{
    */
 
@@ -1496,7 +1664,8 @@ namespace std
   template<typename _IntType = int>
     class uniform_int_distribution
     {
-      __glibcxx_class_requires(_IntType, _IntegerConcept)
+      static_assert(std::is_integral<_IntType>::value,
+                   "template argument not an integral type");
 
     public:
       /** The type of the range of the distribution. */
@@ -1507,7 +1676,8 @@ namespace std
        typedef uniform_int_distribution<_IntType> distribution_type;
 
        explicit
-       param_type(_IntType __a = 0, _IntType __b = 9)
+       param_type(_IntType __a = 0,
+                  _IntType __b = std::numeric_limits<_IntType>::max())
        : _M_a(__a), _M_b(__b)
        {
          _GLIBCXX_DEBUG_ASSERT(_M_a <= _M_b);
@@ -1521,6 +1691,10 @@ namespace std
        b() const
        { return _M_b; }
 
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_a == __p2._M_a && __p1._M_b == __p2._M_b; }
+
       private:
        _IntType _M_a;
        _IntType _M_b;
@@ -1531,7 +1705,8 @@ namespace std
        * @brief Constructs a uniform distribution object.
        */
       explicit
-      uniform_int_distribution(_IntType __a = 0, _IntType __b = 9)
+      uniform_int_distribution(_IntType __a = 0,
+                          _IntType __b = std::numeric_limits<_IntType>::max())
       : _M_param(__a, __b)
       { }
 
@@ -1556,20 +1731,6 @@ namespace std
       b() const
       { return _M_param.b(); }
 
-      /**
-       * @brief Returns the inclusive lower bound of the distribution range.
-       */
-      result_type
-      min() const
-      { return this->a(); }
-
-      /**
-       * @brief Returns the inclusive upper bound of the distribution range.
-       */
-      result_type
-      max() const
-      { return this->b(); }
-
       /**
        * @brief Returns the parameter set of the distribution.
        */
@@ -1586,49 +1747,84 @@ namespace std
       { _M_param = __param; }
 
       /**
-       * Gets a uniformly distributed random number in the range
-       * @f$(min, max)@f$.
+       * @brief Returns the inclusive lower bound of the distribution range.
+       */
+      result_type
+      min() const
+      { return this->a(); }
+
+      /**
+       * @brief Returns the inclusive upper bound of the distribution range.
+       */
+      result_type
+      max() const
+      { return this->b(); }
+
+      /**
+       * @brief Generating functions.
        */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-        { return this->operator()(__urng, this->param()); }
+        { return this->operator()(__urng, _M_param); }
 
-      /**
-       * Gets a uniform random number in the range @f$[0, n)@f$.
-       *
-       * This function is aimed at use with std::random_shuffle.
-       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
+                  const param_type& __p);
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate(__f, __t, __urng, _M_param); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
                   const param_type& __p)
-       {
-         typedef typename _UniformRandomNumberGenerator::result_type
-           _UResult_type;
-         return _M_call(__urng, __p.a(), __p.b(),
-                        typename is_integral<_UResult_type>::type());
-       }
+       { this->__generate_impl(__f, __t, __urng, __p); }
 
-    private:
       template<typename _UniformRandomNumberGenerator>
-       result_type
-       _M_call(_UniformRandomNumberGenerator& __urng,
-               result_type __min, result_type __max, true_type);
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
 
-      template<typename _UniformRandomNumberGenerator>
-       result_type
-       _M_call(_UniformRandomNumberGenerator& __urng,
-               result_type __min, result_type __max, false_type)
-       {
-         return result_type((__urng() - __urng.min())
-                            / (__urng.max() - __urng.min())
-                            * (__max - __min + 1)) + __min;
-       }
+      /**
+       * @brief Return true if two uniform integer distributions have
+       *        the same parameters.
+       */
+      friend bool
+      operator==(const uniform_int_distribution& __d1,
+                const uniform_int_distribution& __d2)
+      { return __d1._M_param == __d2._M_param; }
+
+    private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
 
       param_type _M_param;
     };
 
+  /**
+   * @brief Return true if two uniform integer distributions have
+   *        different parameters.
+   */
+  template<typename _IntType>
+    inline bool
+    operator!=(const std::uniform_int_distribution<_IntType>& __d1,
+              const std::uniform_int_distribution<_IntType>& __d2)
+    { return !(__d1 == __d2); }
+
   /**
    * @brief Inserts a %uniform_int_distribution random number
    *        distribution @p __x into the output stream @p os.
@@ -1669,6 +1865,9 @@ namespace std
   template<typename _RealType = double>
     class uniform_real_distribution
     {
+      static_assert(std::is_floating_point<_RealType>::value,
+                   "template argument not a floating point type");
+
     public:
       /** The type of the range of the distribution. */
       typedef _RealType result_type;
@@ -1693,6 +1892,10 @@ namespace std
        b() const
        { return _M_b; }
 
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_a == __p2._M_a && __p1._M_b == __p2._M_b; }
+
       private:
        _RealType _M_a;
        _RealType _M_b;
@@ -1702,8 +1905,8 @@ namespace std
       /**
        * @brief Constructs a uniform_real_distribution object.
        *
-       * @param __min [IN]  The lower bound of the distribution.
-       * @param __max [IN]  The upper bound of the distribution.
+       * @param __a [IN]  The lower bound of the distribution.
+       * @param __b [IN]  The upper bound of the distribution.
        */
       explicit
       uniform_real_distribution(_RealType __a = _RealType(0),
@@ -1733,25 +1936,11 @@ namespace std
       { return _M_param.b(); }
 
       /**
-       * @brief Returns the inclusive lower bound of the distribution range.
+       * @brief Returns the parameter set of the distribution.
        */
-      result_type
-      min() const
-      { return this->a(); }
-
-      /**
-       * @brief Returns the inclusive upper bound of the distribution range.
-       */
-      result_type
-      max() const
-      { return this->b(); }
-
-      /**
-       * @brief Returns the parameter set of the distribution.
-       */
-      param_type
-      param() const
-      { return _M_param; }
+      param_type
+      param() const
+      { return _M_param; }
 
       /**
        * @brief Sets the parameter set of the distribution.
@@ -1761,10 +1950,27 @@ namespace std
       param(const param_type& __param)
       { _M_param = __param; }
 
+      /**
+       * @brief Returns the inclusive lower bound of the distribution range.
+       */
+      result_type
+      min() const
+      { return this->a(); }
+
+      /**
+       * @brief Returns the inclusive upper bound of the distribution range.
+       */
+      result_type
+      max() const
+      { return this->b(); }
+
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-        { return this->operator()(__urng, this->param()); }
+        { return this->operator()(__urng, _M_param); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
@@ -1776,10 +1982,58 @@ namespace std
          return (__aurng() * (__p.b() - __p.a())) + __p.a();
        }
 
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate(__f, __t, __urng, _M_param); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      /**
+       * @brief Return true if two uniform real distributions have
+       *        the same parameters.
+       */
+      friend bool
+      operator==(const uniform_real_distribution& __d1,
+                const uniform_real_distribution& __d2)
+      { return __d1._M_param == __d2._M_param; }
+
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       param_type _M_param;
     };
 
+  /**
+   * @brief Return true if two uniform real distributions have
+   *        different parameters.
+   */
+  template<typename _IntType>
+    inline bool
+    operator!=(const std::uniform_real_distribution<_IntType>& __d1,
+              const std::uniform_real_distribution<_IntType>& __d2)
+    { return !(__d1 == __d2); }
+
   /**
    * @brief Inserts a %uniform_real_distribution random number
    *        distribution @p __x into the output stream @p __os.
@@ -1809,11 +2063,11 @@ namespace std
     operator>>(std::basic_istream<_CharT, _Traits>&,
               std::uniform_real_distribution<_RealType>&);
 
-  /* @} */ // group std_random_distributions_uniform
+  /* @} */ // group random_distributions_uniform
 
   /**
-   * @addtogroup std_random_distributions_normal Normal Distributions
-   * @ingroup std_random_distributions
+   * @addtogroup random_distributions_normal Normal Distributions
+   * @ingroup random_distributions
    * @{
    */
 
@@ -1821,12 +2075,17 @@ namespace std
    * @brief A normal continuous distribution for random numbers.
    *
    * The formula for the normal probability density function is
-   * @f$ p(x|\mu,\sigma) = \frac{1}{\sigma \sqrt{2 \pi}}
-   *            e^{- \frac{{x - \mu}^ {2}}{2 \sigma ^ {2}} } @f$.
+   * @f[
+   *     p(x|\mu,\sigma) = \frac{1}{\sigma \sqrt{2 \pi}}
+   *            e^{- \frac{{x - \mu}^ {2}}{2 \sigma ^ {2}} } 
+   * @f]
    */
   template<typename _RealType = double>
     class normal_distribution
     {
+      static_assert(std::is_floating_point<_RealType>::value,
+                   "template argument not a floating point type");
+
     public:
       /** The type of the range of the distribution. */
       typedef _RealType result_type;
@@ -1851,6 +2110,11 @@ namespace std
        stddev() const
        { return _M_stddev; }
 
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return (__p1._M_mean == __p2._M_mean
+                 && __p1._M_stddev == __p2._M_stddev); }
+
       private:
        _RealType _M_mean;
        _RealType _M_stddev;
@@ -1858,7 +2122,7 @@ namespace std
 
     public:
       /**
-       * Constructs a normal distribution with parameters @f$ mean @f$ and
+       * Constructs a normal distribution with parameters @f$mean@f$ and
        * standard deviation.
        */
       explicit
@@ -1913,7 +2177,7 @@ namespace std
        */
       result_type
       min() const
-      { return std::numeric_limits<result_type>::min(); }
+      { return std::numeric_limits<result_type>::lowest(); }
 
       /**
        * @brief Returns the least upper bound value of the distribution.
@@ -1922,16 +2186,51 @@ namespace std
       max() const
       { return std::numeric_limits<result_type>::max(); }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+       { return this->operator()(__urng, _M_param); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
                   const param_type& __p);
 
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate(__f, __t, __urng, _M_param); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      /**
+       * @brief Return true if two normal distributions have
+       *        the same parameters and the sequences that would
+       *        be generated are equal.
+       */
+      template<typename _RealType1>
+       friend bool
+        operator==(const std::normal_distribution<_RealType1>& __d1,
+                  const std::normal_distribution<_RealType1>& __d2);
+
       /**
        * @brief Inserts a %normal_distribution random number distribution
        * @p __x into the output stream @p __os.
@@ -1944,8 +2243,8 @@ namespace std
        */
       template<typename _RealType1, typename _CharT, typename _Traits>
        friend std::basic_ostream<_CharT, _Traits>&
-       operator<<(std::basic_ostream<_CharT, _Traits>&,
-                  const std::normal_distribution<_RealType1>&);
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+                  const std::normal_distribution<_RealType1>& __x);
 
       /**
        * @brief Extracts a %normal_distribution random number distribution
@@ -1959,26 +2258,47 @@ namespace std
        */
       template<typename _RealType1, typename _CharT, typename _Traits>
        friend std::basic_istream<_CharT, _Traits>&
-       operator>>(std::basic_istream<_CharT, _Traits>&,
-                  std::normal_distribution<_RealType1>&);
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
+                  std::normal_distribution<_RealType1>& __x);
 
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       param_type  _M_param;
       result_type _M_saved;
       bool        _M_saved_available;
     };
 
+  /**
+   * @brief Return true if two normal distributions are different.
+   */
+  template<typename _RealType>
+    inline bool
+    operator!=(const std::normal_distribution<_RealType>& __d1,
+              const std::normal_distribution<_RealType>& __d2)
+    { return !(__d1 == __d2); }
+
 
   /**
    * @brief A lognormal_distribution random number distribution.
    *
    * The formula for the normal probability mass function is
-   * @f$ p(x|m,s) = \frac{1}{sx\sqrt{2\pi}}
-   *             \exp{-\frac{(\ln{x} - m)^2}{2s^2}} @f$
+   * @f[
+   *     p(x|m,s) = \frac{1}{sx\sqrt{2\pi}}
+   *                \exp{-\frac{(\ln{x} - m)^2}{2s^2}} 
+   * @f]
    */
   template<typename _RealType = double>
     class lognormal_distribution
     {
+      static_assert(std::is_floating_point<_RealType>::value,
+                   "template argument not a floating point type");
+
     public:
       /** The type of the range of the distribution. */
       typedef _RealType result_type;
@@ -2001,6 +2321,10 @@ namespace std
        s() const
        { return _M_s; }
 
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_m == __p2._M_m && __p1._M_s == __p2._M_s; }
+
       private:
        _RealType _M_m;
        _RealType _M_s;
@@ -2064,10 +2388,13 @@ namespace std
       max() const
       { return std::numeric_limits<result_type>::max(); }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+        { return this->operator()(__urng, _M_param); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
@@ -2075,81 +2402,162 @@ namespace std
                   const param_type& __p)
         { return std::exp(__p.s() * _M_nd(__urng) + __p.m()); }
 
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate(__f, __t, __urng, _M_param); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      /**
+       * @brief Return true if two lognormal distributions have
+       *        the same parameters and the sequences that would
+       *        be generated are equal.
+       */
+      friend bool
+      operator==(const lognormal_distribution& __d1,
+                const lognormal_distribution& __d2)
+      { return (__d1._M_param == __d2._M_param
+               && __d1._M_nd == __d2._M_nd); }
+
+      /**
+       * @brief Inserts a %lognormal_distribution random number distribution
+       * @p __x into the output stream @p __os.
+       *
+       * @param __os An output stream.
+       * @param __x  A %lognormal_distribution random number distribution.
+       *
+       * @returns The output stream with the state of @p __x inserted or in
+       * an error state.
+       */
+      template<typename _RealType1, typename _CharT, typename _Traits>
+       friend std::basic_ostream<_CharT, _Traits>&
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+                  const std::lognormal_distribution<_RealType1>& __x);
+
+      /**
+       * @brief Extracts a %lognormal_distribution random number distribution
+       * @p __x from the input stream @p __is.
+       *
+       * @param __is An input stream.
+       * @param __x A %lognormal_distribution random number
+       *            generator engine.
+       *
+       * @returns The input stream with @p __x extracted or in an error state.
+       */
+      template<typename _RealType1, typename _CharT, typename _Traits>
+       friend std::basic_istream<_CharT, _Traits>&
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
+                  std::lognormal_distribution<_RealType1>& __x);
+
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       param_type _M_param;
 
-      normal_distribution<result_type> _M_nd;
+      std::normal_distribution<result_type> _M_nd;
     };
 
   /**
-   * @brief Inserts a %lognormal_distribution random number distribution
-   * @p __x into the output stream @p __os.
-   *
-   * @param __os An output stream.
-   * @param __x  A %lognormal_distribution random number distribution.
-   *
-   * @returns The output stream with the state of @p __x inserted or in
-   * an error state.
-   */
-  template<typename _RealType, typename _CharT, typename _Traits>
-    std::basic_ostream<_CharT, _Traits>&
-    operator<<(std::basic_ostream<_CharT, _Traits>&,
-              const std::lognormal_distribution<_RealType>&);
-
-  /**
-   * @brief Extracts a %lognormal_distribution random number distribution
-   * @p __x from the input stream @p __is.
-   *
-   * @param __is An input stream.
-   * @param __x A %lognormal_distribution random number
-   *            generator engine.
-   *
-   * @returns The input stream with @p __x extracted or in an error state.
+   * @brief Return true if two lognormal distributions are different.
    */
-  template<typename _RealType, typename _CharT, typename _Traits>
-    std::basic_istream<_CharT, _Traits>&
-    operator>>(std::basic_istream<_CharT, _Traits>&,
-              std::lognormal_distribution<_RealType>&);
+  template<typename _RealType>
+    inline bool
+    operator!=(const std::lognormal_distribution<_RealType>& __d1,
+              const std::lognormal_distribution<_RealType>& __d2)
+    { return !(__d1 == __d2); }
 
 
   /**
-   * @brief A chi_squared_distribution random number distribution.
+   * @brief A gamma continuous distribution for random numbers.
    *
-   * The formula for the normal probability mass function is
-   * @f$ p(x|n) = \frac{x^{(n/2) - 1}e^{-x/2}}{\Gamma(n/2) 2^{n/2}} @f$
+   * The formula for the gamma probability density function is:
+   * @f[
+   *     p(x|\alpha,\beta) = \frac{1}{\beta\Gamma(\alpha)}
+   *                         (x/\beta)^{\alpha - 1} e^{-x/\beta} 
+   * @f]
    */
   template<typename _RealType = double>
-    class chi_squared_distribution
+    class gamma_distribution
     {
+      static_assert(std::is_floating_point<_RealType>::value,
+                   "template argument not a floating point type");
+
     public:
       /** The type of the range of the distribution. */
       typedef _RealType result_type;
       /** Parameter type. */
       struct param_type
       {
-       typedef chi_squared_distribution<_RealType> distribution_type;
+       typedef gamma_distribution<_RealType> distribution_type;
+       friend class gamma_distribution<_RealType>;
 
        explicit
-       param_type(_RealType __n = _RealType(1))
-       : _M_n(__n)
-       { }
+       param_type(_RealType __alpha_val = _RealType(1),
+                  _RealType __beta_val = _RealType(1))
+       : _M_alpha(__alpha_val), _M_beta(__beta_val)
+       {
+         _GLIBCXX_DEBUG_ASSERT(_M_alpha > _RealType(0));
+         _M_initialize();
+       }
 
        _RealType
-       n() const
-       { return _M_n; }
+       alpha() const
+       { return _M_alpha; }
+
+       _RealType
+       beta() const
+       { return _M_beta; }
+
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return (__p1._M_alpha == __p2._M_alpha
+                 && __p1._M_beta == __p2._M_beta); }
 
       private:
-       _RealType _M_n;
+       void
+       _M_initialize();
+
+       _RealType _M_alpha;
+       _RealType _M_beta;
+
+       _RealType _M_malpha, _M_a2;
       };
 
+    public:
+      /**
+       * @brief Constructs a gamma distribution with parameters
+       * @f$\alpha@f$ and @f$\beta@f$.
+       */
       explicit
-      chi_squared_distribution(_RealType __n = _RealType(1))
-      : _M_param(__n)
+      gamma_distribution(_RealType __alpha_val = _RealType(1),
+                        _RealType __beta_val = _RealType(1))
+      : _M_param(__alpha_val, __beta_val), _M_nd()
       { }
 
       explicit
-      chi_squared_distribution(const param_type& __p)
-      : _M_param(__p)
+      gamma_distribution(const param_type& __p)
+      : _M_param(__p), _M_nd()
       { }
 
       /**
@@ -2157,14 +2565,21 @@ namespace std
        */
       void
       reset()
-      { }
+      { _M_nd.reset(); }
 
       /**
-       *
+       * @brief Returns the @f$\alpha@f$ of the distribution.
        */
       _RealType
-      n() const
-      { return _M_param.n(); }
+      alpha() const
+      { return _M_param.alpha(); }
+
+      /**
+       * @brief Returns the @f$\beta@f$ of the distribution.
+       */
+      _RealType
+      beta() const
+      { return _M_param.beta(); }
 
       /**
        * @brief Returns the parameter set of the distribution.
@@ -2195,60 +2610,326 @@ namespace std
       max() const
       { return std::numeric_limits<result_type>::max(); }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+       { return this->operator()(__urng, _M_param); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
                   const param_type& __p);
 
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate(__f, __t, __urng, _M_param); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      /**
+       * @brief Return true if two gamma distributions have the same
+       *        parameters and the sequences that would be generated
+       *        are equal.
+       */
+      friend bool
+      operator==(const gamma_distribution& __d1,
+                const gamma_distribution& __d2)
+      { return (__d1._M_param == __d2._M_param
+               && __d1._M_nd == __d2._M_nd); }
+
+      /**
+       * @brief Inserts a %gamma_distribution random number distribution
+       * @p __x into the output stream @p __os.
+       *
+       * @param __os An output stream.
+       * @param __x  A %gamma_distribution random number distribution.
+       *
+       * @returns The output stream with the state of @p __x inserted or in
+       * an error state.
+       */
+      template<typename _RealType1, typename _CharT, typename _Traits>
+       friend std::basic_ostream<_CharT, _Traits>&
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+                  const std::gamma_distribution<_RealType1>& __x);
+
+      /**
+       * @brief Extracts a %gamma_distribution random number distribution
+       * @p __x from the input stream @p __is.
+       *
+       * @param __is An input stream.
+       * @param __x  A %gamma_distribution random number generator engine.
+       *
+       * @returns The input stream with @p __x extracted or in an error state.
+       */
+      template<typename _RealType1, typename _CharT, typename _Traits>
+       friend std::basic_istream<_CharT, _Traits>&
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
+                  std::gamma_distribution<_RealType1>& __x);
+
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       param_type _M_param;
-    };
 
-  /**
-   * @brief Inserts a %chi_squared_distribution random number distribution
-   * @p __x into the output stream @p __os.
-   *
-   * @param __os An output stream.
-   * @param __x  A %chi_squared_distribution random number distribution.
-   *
-   * @returns The output stream with the state of @p __x inserted or in
-   * an error state.
-   */
-  template<typename _RealType, typename _CharT, typename _Traits>
-    std::basic_ostream<_CharT, _Traits>&
-    operator<<(std::basic_ostream<_CharT, _Traits>&,
-              const std::chi_squared_distribution<_RealType>&);
+      std::normal_distribution<result_type> _M_nd;
+    };
 
   /**
-   * @brief Extracts a %chi_squared_distribution random number distribution
-   * @p __x from the input stream @p __is.
-   *
-   * @param __is An input stream.
-   * @param __x A %chi_squared_distribution random number
-   *            generator engine.
-   *
-   * @returns The input stream with @p __x extracted or in an error state.
+   * @brief Return true if two gamma distributions are different.
    */
-  template<typename _RealType, typename _CharT, typename _Traits>
-    std::basic_istream<_CharT, _Traits>&
-    operator>>(std::basic_istream<_CharT, _Traits>&,
-              std::chi_squared_distribution<_RealType>&);
+   template<typename _RealType>
+     inline bool
+     operator!=(const std::gamma_distribution<_RealType>& __d1,
+               const std::gamma_distribution<_RealType>& __d2)
+    { return !(__d1 == __d2); }
 
 
   /**
-   * @brief A cauchy_distribution random number distribution.
+   * @brief A chi_squared_distribution random number distribution.
    *
    * The formula for the normal probability mass function is
-   * @f$ p(x|a,b) = (\pi b (1 + (\frac{x-a}{b})^2))^{-1} @f$
+   * @f$p(x|n) = \frac{x^{(n/2) - 1}e^{-x/2}}{\Gamma(n/2) 2^{n/2}}@f$
    */
   template<typename _RealType = double>
-    class cauchy_distribution
+    class chi_squared_distribution
     {
+      static_assert(std::is_floating_point<_RealType>::value,
+                   "template argument not a floating point type");
+
+    public:
+      /** The type of the range of the distribution. */
+      typedef _RealType result_type;
+      /** Parameter type. */
+      struct param_type
+      {
+       typedef chi_squared_distribution<_RealType> distribution_type;
+
+       explicit
+       param_type(_RealType __n = _RealType(1))
+       : _M_n(__n)
+       { }
+
+       _RealType
+       n() const
+       { return _M_n; }
+
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_n == __p2._M_n; }
+
+      private:
+       _RealType _M_n;
+      };
+
+      explicit
+      chi_squared_distribution(_RealType __n = _RealType(1))
+      : _M_param(__n), _M_gd(__n / 2)
+      { }
+
+      explicit
+      chi_squared_distribution(const param_type& __p)
+      : _M_param(__p), _M_gd(__p.n() / 2)
+      { }
+
+      /**
+       * @brief Resets the distribution state.
+       */
+      void
+      reset()
+      { _M_gd.reset(); }
+
+      /**
+       *
+       */
+      _RealType
+      n() const
+      { return _M_param.n(); }
+
+      /**
+       * @brief Returns the parameter set of the distribution.
+       */
+      param_type
+      param() const
+      { return _M_param; }
+
+      /**
+       * @brief Sets the parameter set of the distribution.
+       * @param __param The new parameter set of the distribution.
+       */
+      void
+      param(const param_type& __param)
+      { _M_param = __param; }
+
+      /**
+       * @brief Returns the greatest lower bound value of the distribution.
+       */
+      result_type
+      min() const
+      { return result_type(0); }
+
+      /**
+       * @brief Returns the least upper bound value of the distribution.
+       */
+      result_type
+      max() const
+      { return std::numeric_limits<result_type>::max(); }
+
+      /**
+       * @brief Generating functions.
+       */
+      template<typename _UniformRandomNumberGenerator>
+       result_type
+       operator()(_UniformRandomNumberGenerator& __urng)
+       { return 2 * _M_gd(__urng); }
+
+      template<typename _UniformRandomNumberGenerator>
+       result_type
+       operator()(_UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+        {
+         typedef typename std::gamma_distribution<result_type>::param_type
+           param_type;
+         return 2 * _M_gd(__urng, param_type(__p.n() / 2));
+       }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+        { this->__generate_impl(__f, __t, __urng); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { typename std::gamma_distribution<result_type>::param_type
+           __p2(__p.n() / 2);
+         this->__generate_impl(__f, __t, __urng, __p2); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng)
+        { this->__generate_impl(__f, __t, __urng); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { typename std::gamma_distribution<result_type>::param_type
+           __p2(__p.n() / 2);
+         this->__generate_impl(__f, __t, __urng, __p2); }
+
+      /**
+       * @brief Return true if two Chi-squared distributions have
+       *        the same parameters and the sequences that would be
+       *        generated are equal.
+       */
+      friend bool
+      operator==(const chi_squared_distribution& __d1,
+                const chi_squared_distribution& __d2)
+      { return __d1._M_param == __d2._M_param && __d1._M_gd == __d2._M_gd; }
+
+      /**
+       * @brief Inserts a %chi_squared_distribution random number distribution
+       * @p __x into the output stream @p __os.
+       *
+       * @param __os An output stream.
+       * @param __x  A %chi_squared_distribution random number distribution.
+       *
+       * @returns The output stream with the state of @p __x inserted or in
+       * an error state.
+       */
+      template<typename _RealType1, typename _CharT, typename _Traits>
+       friend std::basic_ostream<_CharT, _Traits>&
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+                  const std::chi_squared_distribution<_RealType1>& __x);
+
+      /**
+       * @brief Extracts a %chi_squared_distribution random number distribution
+       * @p __x from the input stream @p __is.
+       *
+       * @param __is An input stream.
+       * @param __x A %chi_squared_distribution random number
+       *            generator engine.
+       *
+       * @returns The input stream with @p __x extracted or in an error state.
+       */
+      template<typename _RealType1, typename _CharT, typename _Traits>
+       friend std::basic_istream<_CharT, _Traits>&
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
+                  std::chi_squared_distribution<_RealType1>& __x);
+
+    private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng);
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const typename
+                       std::gamma_distribution<result_type>::param_type& __p);
+
+      param_type _M_param;
+
+      std::gamma_distribution<result_type> _M_gd;
+    };
+
+  /**
+   * @brief Return true if two Chi-squared distributions are different.
+   */
+  template<typename _RealType>
+    inline bool
+    operator!=(const std::chi_squared_distribution<_RealType>& __d1,
+              const std::chi_squared_distribution<_RealType>& __d2)
+    { return !(__d1 == __d2); }
+
+
+  /**
+   * @brief A cauchy_distribution random number distribution.
+   *
+   * The formula for the normal probability mass function is
+   * @f$p(x|a,b) = (\pi b (1 + (\frac{x-a}{b})^2))^{-1}@f$
+   */
+  template<typename _RealType = double>
+    class cauchy_distribution
+    {
+      static_assert(std::is_floating_point<_RealType>::value,
+                   "template argument not a floating point type");
+
     public:
       /** The type of the range of the distribution. */
       typedef _RealType result_type;
@@ -2271,6 +2952,10 @@ namespace std
        b() const
        { return _M_b; }
 
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_a == __p2._M_a && __p1._M_b == __p2._M_b; }
+
       private:
        _RealType _M_a;
        _RealType _M_b;
@@ -2325,7 +3010,7 @@ namespace std
        */
       result_type
       min() const
-      { return std::numeric_limits<result_type>::min(); }
+      { return std::numeric_limits<result_type>::lowest(); }
 
       /**
        * @brief Returns the least upper bound value of the distribution.
@@ -2334,20 +3019,71 @@ namespace std
       max() const
       { return std::numeric_limits<result_type>::max(); }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+       { return this->operator()(__urng, _M_param); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
                   const param_type& __p);
 
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate(__f, __t, __urng, _M_param); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      /**
+       * @brief Return true if two Cauchy distributions have
+       *        the same parameters.
+       */
+      friend bool
+      operator==(const cauchy_distribution& __d1,
+                const cauchy_distribution& __d2)
+      { return __d1._M_param == __d2._M_param; }
+
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       param_type _M_param;
     };
 
+  /**
+   * @brief Return true if two Cauchy distributions have
+   *        different parameters.
+   */
+  template<typename _RealType>
+    inline bool
+    operator!=(const std::cauchy_distribution<_RealType>& __d1,
+              const std::cauchy_distribution<_RealType>& __d2)
+    { return !(__d1 == __d2); }
+
   /**
    * @brief Inserts a %cauchy_distribution random number distribution
    * @p __x into the output stream @p __os.
@@ -2360,8 +3096,8 @@ namespace std
    */
   template<typename _RealType, typename _CharT, typename _Traits>
     std::basic_ostream<_CharT, _Traits>&
-    operator<<(std::basic_ostream<_CharT, _Traits>&,
-              const std::cauchy_distribution<_RealType>&);
+    operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+              const std::cauchy_distribution<_RealType>& __x);
 
   /**
    * @brief Extracts a %cauchy_distribution random number distribution
@@ -2375,21 +3111,26 @@ namespace std
    */
   template<typename _RealType, typename _CharT, typename _Traits>
     std::basic_istream<_CharT, _Traits>&
-    operator>>(std::basic_istream<_CharT, _Traits>&,
-              std::cauchy_distribution<_RealType>&);
+    operator>>(std::basic_istream<_CharT, _Traits>& __is,
+              std::cauchy_distribution<_RealType>& __x);
 
 
   /**
    * @brief A fisher_f_distribution random number distribution.
    *
    * The formula for the normal probability mass function is
-   * @f$ p(x|m,n) = \frac{\Gamma((m+n)/2)}{\Gamma(m/2)\Gamma(n/2)}
+   * @f[
+   *     p(x|m,n) = \frac{\Gamma((m+n)/2)}{\Gamma(m/2)\Gamma(n/2)}
    *                (\frac{m}{n})^{m/2} x^{(m/2)-1}
-   *                (1 + \frac{mx}{n})^{-(m+n)/2} @f$
+   *                (1 + \frac{mx}{n})^{-(m+n)/2} 
+   * @f]
    */
   template<typename _RealType = double>
     class fisher_f_distribution
     {
+      static_assert(std::is_floating_point<_RealType>::value,
+                   "template argument not a floating point type");
+
     public:
       /** The type of the range of the distribution. */
       typedef _RealType result_type;
@@ -2412,6 +3153,10 @@ namespace std
        n() const
        { return _M_n; }
 
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_m == __p2._M_m && __p1._M_n == __p2._M_n; }
+
       private:
        _RealType _M_m;
        _RealType _M_n;
@@ -2420,12 +3165,12 @@ namespace std
       explicit
       fisher_f_distribution(_RealType __m = _RealType(1),
                            _RealType __n = _RealType(1))
-      : _M_param(__m, __n)
+      : _M_param(__m, __n), _M_gd_x(__m / 2), _M_gd_y(__n / 2)
       { }
 
       explicit
       fisher_f_distribution(const param_type& __p)
-      : _M_param(__p)
+      : _M_param(__p), _M_gd_x(__p.m() / 2), _M_gd_y(__p.n() / 2)
       { }
 
       /**
@@ -2433,7 +3178,10 @@ namespace std
        */
       void
       reset()
-      { }
+      {
+       _M_gd_x.reset();
+       _M_gd_y.reset();
+      }
 
       /**
        *
@@ -2475,61 +3223,138 @@ namespace std
       max() const
       { return std::numeric_limits<result_type>::max(); }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+       { return (_M_gd_x(__urng) * n()) / (_M_gd_y(__urng) * m()); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
-                  const param_type& __p);
+                  const param_type& __p)
+        {
+         typedef typename std::gamma_distribution<result_type>::param_type
+           param_type;
+         return ((_M_gd_x(__urng, param_type(__p.m() / 2)) * n())
+                 / (_M_gd_y(__urng, param_type(__p.n() / 2)) * m()));
+       }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate_impl(__f, __t, __urng); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate_impl(__f, __t, __urng); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      /**
+       * @brief Return true if two Fisher f distributions have
+       *        the same parameters and the sequences that would
+       *        be generated are equal.
+       */
+      friend bool
+      operator==(const fisher_f_distribution& __d1,
+                const fisher_f_distribution& __d2)
+      { return (__d1._M_param == __d2._M_param
+               && __d1._M_gd_x == __d2._M_gd_x
+               && __d1._M_gd_y == __d2._M_gd_y); }
+
+      /**
+       * @brief Inserts a %fisher_f_distribution random number distribution
+       * @p __x into the output stream @p __os.
+       *
+       * @param __os An output stream.
+       * @param __x  A %fisher_f_distribution random number distribution.
+       *
+       * @returns The output stream with the state of @p __x inserted or in
+       * an error state.
+       */
+      template<typename _RealType1, typename _CharT, typename _Traits>
+       friend std::basic_ostream<_CharT, _Traits>&
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+                  const std::fisher_f_distribution<_RealType1>& __x);
+
+      /**
+       * @brief Extracts a %fisher_f_distribution random number distribution
+       * @p __x from the input stream @p __is.
+       *
+       * @param __is An input stream.
+       * @param __x A %fisher_f_distribution random number
+       *            generator engine.
+       *
+       * @returns The input stream with @p __x extracted or in an error state.
+       */
+      template<typename _RealType1, typename _CharT, typename _Traits>
+       friend std::basic_istream<_CharT, _Traits>&
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
+                  std::fisher_f_distribution<_RealType1>& __x);
 
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng);
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       param_type _M_param;
-    };
 
-  /**
-   * @brief Inserts a %fisher_f_distribution random number distribution
-   * @p __x into the output stream @p __os.
-   *
-   * @param __os An output stream.
-   * @param __x  A %fisher_f_distribution random number distribution.
-   *
-   * @returns The output stream with the state of @p __x inserted or in
-   * an error state.
-   */
-  template<typename _RealType, typename _CharT, typename _Traits>
-    std::basic_ostream<_CharT, _Traits>&
-    operator<<(std::basic_ostream<_CharT, _Traits>&,
-              const std::fisher_f_distribution<_RealType>&);
+      std::gamma_distribution<result_type> _M_gd_x, _M_gd_y;
+    };
 
   /**
-   * @brief Extracts a %fisher_f_distribution random number distribution
-   * @p __x from the input stream @p __is.
-   *
-   * @param __is An input stream.
-   * @param __x A %fisher_f_distribution random number
-   *            generator engine.
-   *
-   * @returns The input stream with @p __x extracted or in an error state.
+   * @brief Return true if two Fisher f distributions are different.
    */
-  template<typename _RealType, typename _CharT, typename _Traits>
-    std::basic_istream<_CharT, _Traits>&
-    operator>>(std::basic_istream<_CharT, _Traits>&,
-              std::fisher_f_distribution<_RealType>&);
-
+  template<typename _RealType>
+    inline bool
+    operator!=(const std::fisher_f_distribution<_RealType>& __d1,
+              const std::fisher_f_distribution<_RealType>& __d2)
+    { return !(__d1 == __d2); }
 
   /**
    * @brief A student_t_distribution random number distribution.
    *
-   * The formula for the normal probability mass function is
-   * @f$ p(x|n) = \frac{1}{\sqrt(n\pi)} \frac{\Gamma((n+1)/2)}{\Gamma(n/2)}
-   *              (1 + \frac{x^2}{n}) ^{-(n+1)/2} @f$
+   * The formula for the normal probability mass function is:
+   * @f[
+   *     p(x|n) = \frac{1}{\sqrt(n\pi)} \frac{\Gamma((n+1)/2)}{\Gamma(n/2)}
+   *              (1 + \frac{x^2}{n}) ^{-(n+1)/2} 
+   * @f]
    */
   template<typename _RealType = double>
     class student_t_distribution
     {
+      static_assert(std::is_floating_point<_RealType>::value,
+                   "template argument not a floating point type");
+
     public:
       /** The type of the range of the distribution. */
       typedef _RealType result_type;
@@ -2547,18 +3372,22 @@ namespace std
        n() const
        { return _M_n; }
 
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_n == __p2._M_n; }
+
       private:
        _RealType _M_n;
       };
 
       explicit
       student_t_distribution(_RealType __n = _RealType(1))
-      : _M_param(__n), _M_nd()
+      : _M_param(__n), _M_nd(), _M_gd(__n / 2, 2)
       { }
 
       explicit
       student_t_distribution(const param_type& __p)
-      : _M_param(__p), _M_nd()
+      : _M_param(__p), _M_nd(), _M_gd(__p.n() / 2, 2)
       { }
 
       /**
@@ -2566,7 +3395,10 @@ namespace std
        */
       void
       reset()
-      { _M_nd.reset(); }
+      {
+       _M_nd.reset();
+       _M_gd.reset();
+      }
 
       /**
        *
@@ -2595,7 +3427,7 @@ namespace std
        */
       result_type
       min() const
-      { return std::numeric_limits<result_type>::min(); }
+      { return std::numeric_limits<result_type>::lowest(); }
 
       /**
        * @brief Returns the least upper bound value of the distribution.
@@ -2604,65 +3436,137 @@ namespace std
       max() const
       { return std::numeric_limits<result_type>::max(); }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
-       operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+        operator()(_UniformRandomNumberGenerator& __urng)
+        { return _M_nd(__urng) * std::sqrt(n() / _M_gd(__urng)); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
-                  const param_type& __p);
+                  const param_type& __p)
+        {
+         typedef typename std::gamma_distribution<result_type>::param_type
+           param_type;
+       
+         const result_type __g = _M_gd(__urng, param_type(__p.n() / 2, 2));
+         return _M_nd(__urng) * std::sqrt(__p.n() / __g);
+        }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate_impl(__f, __t, __urng); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate_impl(__f, __t, __urng); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      /**
+       * @brief Return true if two Student t distributions have
+       *        the same parameters and the sequences that would
+       *        be generated are equal.
+       */
+      friend bool
+      operator==(const student_t_distribution& __d1,
+                const student_t_distribution& __d2)
+      { return (__d1._M_param == __d2._M_param
+               && __d1._M_nd == __d2._M_nd && __d1._M_gd == __d2._M_gd); }
+
+      /**
+       * @brief Inserts a %student_t_distribution random number distribution
+       * @p __x into the output stream @p __os.
+       *
+       * @param __os An output stream.
+       * @param __x  A %student_t_distribution random number distribution.
+       *
+       * @returns The output stream with the state of @p __x inserted or in
+       * an error state.
+       */
+      template<typename _RealType1, typename _CharT, typename _Traits>
+       friend std::basic_ostream<_CharT, _Traits>&
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+                  const std::student_t_distribution<_RealType1>& __x);
+
+      /**
+       * @brief Extracts a %student_t_distribution random number distribution
+       * @p __x from the input stream @p __is.
+       *
+       * @param __is An input stream.
+       * @param __x A %student_t_distribution random number
+       *            generator engine.
+       *
+       * @returns The input stream with @p __x extracted or in an error state.
+       */
+      template<typename _RealType1, typename _CharT, typename _Traits>
+       friend std::basic_istream<_CharT, _Traits>&
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
+                  std::student_t_distribution<_RealType1>& __x);
 
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng);
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       param_type _M_param;
 
-      normal_distribution<result_type> _M_nd;
+      std::normal_distribution<result_type> _M_nd;
+      std::gamma_distribution<result_type> _M_gd;
     };
 
   /**
-   * @brief Inserts a %student_t_distribution random number distribution
-   * @p __x into the output stream @p __os.
-   *
-   * @param __os An output stream.
-   * @param __x  A %student_t_distribution random number distribution.
-   *
-   * @returns The output stream with the state of @p __x inserted or in
-   * an error state.
+   * @brief Return true if two Student t distributions are different.
    */
-  template<typename _RealType, typename _CharT, typename _Traits>
-    std::basic_ostream<_CharT, _Traits>&
-    operator<<(std::basic_ostream<_CharT, _Traits>&,
-              const std::student_t_distribution<_RealType>&);
+  template<typename _RealType>
+    inline bool
+    operator!=(const std::student_t_distribution<_RealType>& __d1,
+              const std::student_t_distribution<_RealType>& __d2)
+    { return !(__d1 == __d2); }
 
-  /**
-   * @brief Extracts a %student_t_distribution random number distribution
-   * @p __x from the input stream @p __is.
-   *
-   * @param __is An input stream.
-   * @param __x A %student_t_distribution random number
-   *            generator engine.
-   *
-   * @returns The input stream with @p __x extracted or in an error state.
-   */
-  template<typename _RealType, typename _CharT, typename _Traits>
-    std::basic_istream<_CharT, _Traits>&
-    operator>>(std::basic_istream<_CharT, _Traits>&,
-              std::student_t_distribution<_RealType>&);
 
-  /* @} */ // group std_random_distributions_normal
+  /* @} */ // group random_distributions_normal
 
   /**
-   * @addtogroup std_random_distributions_bernoulli Bernoulli Distributions
-   * @ingroup std_random_distributions
+   * @addtogroup random_distributions_bernoulli Bernoulli Distributions
+   * @ingroup random_distributions
    * @{
    */
 
   /**
    * @brief A Bernoulli random number distribution.
    *
-   * Generates a sequence of true and false values with likelihood @f$ p @f$
-   * that true will come up and @f$ (1 - p) @f$ that false will appear.
+   * Generates a sequence of true and false values with likelihood @f$p@f$
+   * that true will come up and @f$(1 - p)@f$ that false will appear.
    */
   class bernoulli_distribution
   {
@@ -2685,6 +3589,10 @@ namespace std
       p() const
       { return _M_p; }
 
+      friend bool
+      operator==(const param_type& __p1, const param_type& __p2)
+      { return __p1._M_p == __p2._M_p; }
+
     private:
       double _M_p;
     };
@@ -2694,7 +3602,7 @@ namespace std
      * @brief Constructs a Bernoulli distribution with likelihood @p p.
      *
      * @param __p  [IN]  The likelihood of a true result being returned.
-     *                   Must be in the interval @f$ [0, 1] @f$.
+     *                   Must be in the interval @f$[0, 1]@f$.
      */
     explicit
     bernoulli_distribution(double __p = 0.5)
@@ -2751,12 +3659,12 @@ namespace std
     { return std::numeric_limits<result_type>::max(); }
 
     /**
-     * @brief Returns the next value in the Bernoullian sequence.
+     * @brief Generating functions.
      */
     template<typename _UniformRandomNumberGenerator>
       result_type
       operator()(_UniformRandomNumberGenerator& __urng)
-      { return this->operator()(__urng, this->param()); }
+      { return this->operator()(__urng, _M_param); }
 
     template<typename _UniformRandomNumberGenerator>
       result_type
@@ -2771,10 +3679,56 @@ namespace std
        return false;
       }
 
+    template<typename _ForwardIterator,
+            typename _UniformRandomNumberGenerator>
+      void
+      __generate(_ForwardIterator __f, _ForwardIterator __t,
+                _UniformRandomNumberGenerator& __urng)
+      { this->__generate(__f, __t, __urng, _M_param); }
+
+    template<typename _ForwardIterator,
+            typename _UniformRandomNumberGenerator>
+      void
+      __generate(_ForwardIterator __f, _ForwardIterator __t,
+                _UniformRandomNumberGenerator& __urng, const param_type& __p)
+      { this->__generate_impl(__f, __t, __urng, __p); }
+
+    template<typename _UniformRandomNumberGenerator>
+      void
+      __generate(result_type* __f, result_type* __t,
+                _UniformRandomNumberGenerator& __urng,
+                const param_type& __p)
+      { this->__generate_impl(__f, __t, __urng, __p); }
+
+    /**
+     * @brief Return true if two Bernoulli distributions have
+     *        the same parameters.
+     */
+    friend bool
+    operator==(const bernoulli_distribution& __d1,
+              const bernoulli_distribution& __d2)
+    { return __d1._M_param == __d2._M_param; }
+
   private:
+    template<typename _ForwardIterator,
+            typename _UniformRandomNumberGenerator>
+      void
+      __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                     _UniformRandomNumberGenerator& __urng,
+                     const param_type& __p);
+
     param_type _M_param;
   };
 
+  /**
+   * @brief Return true if two Bernoulli distributions have
+   *        different parameters.
+   */
+  inline bool
+  operator!=(const std::bernoulli_distribution& __d1,
+            const std::bernoulli_distribution& __d2)
+  { return !(__d1 == __d2); }
+
   /**
    * @brief Inserts a %bernoulli_distribution random number distribution
    * @p __x into the output stream @p __os.
@@ -2787,8 +3741,8 @@ namespace std
    */
   template<typename _CharT, typename _Traits>
     std::basic_ostream<_CharT, _Traits>&
-    operator<<(std::basic_ostream<_CharT, _Traits>&,
-              const std::bernoulli_distribution&);
+    operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+              const std::bernoulli_distribution& __x);
 
   /**
    * @brief Extracts a %bernoulli_distribution random number distribution
@@ -2815,13 +3769,14 @@ namespace std
    * @brief A discrete binomial random number distribution.
    *
    * The formula for the binomial probability density function is
-   * @f$ p(i|t,p) = \binom{n}{i} p^i (1 - p)^{t - i} @f$ where @f$ t @f$
-   * and @f$ p @f$ are the parameters of the distribution.
+   * @f$p(i|t,p) = \binom{t}{i} p^i (1 - p)^{t - i}@f$ where @f$t@f$
+   * and @f$p@f$ are the parameters of the distribution.
    */
   template<typename _IntType = int>
     class binomial_distribution
     {
-      __glibcxx_class_requires(_IntType, _IntegerConcept)
+      static_assert(std::is_integral<_IntType>::value,
+                   "template argument not an integral type");
 
     public:
       /** The type of the range of the distribution. */
@@ -2850,6 +3805,10 @@ namespace std
        p() const
        { return _M_p; }
 
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_t == __p2._M_t && __p1._M_p == __p2._M_p; }
+
       private:
        void
        _M_initialize();
@@ -2927,16 +3886,55 @@ namespace std
       max() const
       { return _M_param.t(); }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+       { return this->operator()(__urng, _M_param); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
                   const param_type& __p);
 
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate(__f, __t, __urng, _M_param); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      /**
+       * @brief Return true if two binomial distributions have
+       *        the same parameters and the sequences that would
+       *        be generated are equal.
+       */
+       friend bool
+        operator==(const binomial_distribution& __d1,
+                  const binomial_distribution& __d2)
+#ifdef _GLIBCXX_USE_C99_MATH_TR1
+       { return __d1._M_param == __d2._M_param && __d1._M_nd == __d2._M_nd; }
+#else
+        { return __d1._M_param == __d2._M_param; }
+#endif
+
       /**
        * @brief Inserts a %binomial_distribution random number distribution
        * @p __x into the output stream @p __os.
@@ -2950,8 +3948,8 @@ namespace std
       template<typename _IntType1,
               typename _CharT, typename _Traits>
        friend std::basic_ostream<_CharT, _Traits>&
-       operator<<(std::basic_ostream<_CharT, _Traits>&,
-                  const std::binomial_distribution<_IntType1>&);
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+                  const std::binomial_distribution<_IntType1>& __x);
 
       /**
        * @brief Extracts a %binomial_distribution random number distribution
@@ -2966,32 +3964,50 @@ namespace std
       template<typename _IntType1,
               typename _CharT, typename _Traits>
        friend std::basic_istream<_CharT, _Traits>&
-       operator>>(std::basic_istream<_CharT, _Traits>&,
-                  std::binomial_distribution<_IntType1>&);
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
+                  std::binomial_distribution<_IntType1>& __x);
 
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       template<typename _UniformRandomNumberGenerator>
        result_type
-       _M_waiting(_UniformRandomNumberGenerator& __urng, _IntType __t);
+       _M_waiting(_UniformRandomNumberGenerator& __urng,
+                  _IntType __t, double __q);
 
       param_type _M_param;
 
       // NB: Unused when _GLIBCXX_USE_C99_MATH_TR1 is undefined.
-      normal_distribution<double> _M_nd;
+      std::normal_distribution<double> _M_nd;
     };
 
+  /**
+   * @brief Return true if two binomial distributions are different.
+   */
+  template<typename _IntType>
+    inline bool
+    operator!=(const std::binomial_distribution<_IntType>& __d1,
+              const std::binomial_distribution<_IntType>& __d2)
+    { return !(__d1 == __d2); }
+
 
   /**
    * @brief A discrete geometric random number distribution.
    *
    * The formula for the geometric probability density function is
-   * @f$ p(i|p) = (1 - p)p^{i-1} @f$ where @f$ p @f$ is the parameter of the
+   * @f$p(i|p) = p(1 - p)^{i}@f$ where @f$p@f$ is the parameter of the
    * distribution.
    */
   template<typename _IntType = int>
     class geometric_distribution
     {
-      __glibcxx_class_requires(_IntType, _IntegerConcept)
+      static_assert(std::is_integral<_IntType>::value,
+                   "template argument not an integral type");
 
     public:
       /** The type of the range of the distribution. */
@@ -3006,8 +4022,7 @@ namespace std
        param_type(double __p = 0.5)
        : _M_p(__p)
        {
-         _GLIBCXX_DEBUG_ASSERT((_M_p >= 0.0)
-                            && (_M_p <= 1.0));
+         _GLIBCXX_DEBUG_ASSERT((_M_p > 0.0) && (_M_p < 1.0));
          _M_initialize();
        }
 
@@ -3015,14 +4030,18 @@ namespace std
        p() const
        { return _M_p; }
 
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_p == __p2._M_p; }
+
       private:
        void
        _M_initialize()
-       { _M_log_p = std::log(_M_p); }
+       { _M_log_1_p = std::log(1.0 - _M_p); }
 
        double _M_p;
 
-       double _M_log_p;
+       double _M_log_1_p;
       };
 
       // constructors and member function
@@ -3080,20 +4099,71 @@ namespace std
       max() const
       { return std::numeric_limits<result_type>::max(); }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+       { return this->operator()(__urng, _M_param); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
                   const param_type& __p);
 
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate(__f, __t, __urng, _M_param); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      /**
+       * @brief Return true if two geometric distributions have
+       *        the same parameters.
+       */
+      friend bool
+      operator==(const geometric_distribution& __d1,
+                const geometric_distribution& __d2)
+      { return __d1._M_param == __d2._M_param; }
+
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       param_type _M_param;
     };
 
+  /**
+   * @brief Return true if two geometric distributions have
+   *        different parameters.
+   */
+  template<typename _IntType>
+    inline bool
+    operator!=(const std::geometric_distribution<_IntType>& __d1,
+              const std::geometric_distribution<_IntType>& __d2)
+    { return !(__d1 == __d2); }
+
   /**
    * @brief Inserts a %geometric_distribution random number distribution
    * @p __x into the output stream @p __os.
@@ -3107,8 +4177,8 @@ namespace std
   template<typename _IntType,
           typename _CharT, typename _Traits>
     std::basic_ostream<_CharT, _Traits>&
-    operator<<(std::basic_ostream<_CharT, _Traits>&,
-              const std::geometric_distribution<_IntType>&);
+    operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+              const std::geometric_distribution<_IntType>& __x);
 
   /**
    * @brief Extracts a %geometric_distribution random number distribution
@@ -3122,21 +4192,22 @@ namespace std
   template<typename _IntType,
           typename _CharT, typename _Traits>
     std::basic_istream<_CharT, _Traits>&
-    operator>>(std::basic_istream<_CharT, _Traits>&,
-              std::geometric_distribution<_IntType>&);
+    operator>>(std::basic_istream<_CharT, _Traits>& __is,
+              std::geometric_distribution<_IntType>& __x);
 
 
   /**
    * @brief A negative_binomial_distribution random number distribution.
    *
    * The formula for the negative binomial probability mass function is
-   * @f$ p(i) = \binom{n}{i} p^i (1 - p)^{t - i} @f$ where @f$ t @f$
-   * and @f$ p @f$ are the parameters of the distribution.
+   * @f$p(i) = \binom{n}{i} p^i (1 - p)^{t - i}@f$ where @f$t@f$
+   * and @f$p@f$ are the parameters of the distribution.
    */
   template<typename _IntType = int>
     class negative_binomial_distribution
     {
-      __glibcxx_class_requires(_IntType, _IntegerConcept)
+      static_assert(std::is_integral<_IntType>::value,
+                   "template argument not an integral type");
 
     public:
       /** The type of the range of the distribution. */
@@ -3149,7 +4220,9 @@ namespace std
        explicit
        param_type(_IntType __k = 1, double __p = 0.5)
        : _M_k(__k), _M_p(__p)
-       { }
+       {
+         _GLIBCXX_DEBUG_ASSERT((_M_k > 0) && (_M_p > 0.0) && (_M_p <= 1.0));
+       }
 
        _IntType
        k() const
@@ -3159,6 +4232,10 @@ namespace std
        p() const
        { return _M_p; }
 
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_k == __p2._M_k && __p1._M_p == __p2._M_p; }
+
       private:
        _IntType _M_k;
        double _M_p;
@@ -3166,12 +4243,12 @@ namespace std
 
       explicit
       negative_binomial_distribution(_IntType __k = 1, double __p = 0.5)
-      : _M_param(__k, __p)
+      : _M_param(__k, __p), _M_gd(__k, (1.0 - __p) / __p)
       { }
 
       explicit
       negative_binomial_distribution(const param_type& __p)
-      : _M_param(__p)
+      : _M_param(__p), _M_gd(__p.k(), (1.0 - __p.p()) / __p.p())
       { }
 
       /**
@@ -3179,17 +4256,17 @@ namespace std
        */
       void
       reset()
-      { }
+      { _M_gd.reset(); }
 
       /**
-       * @brief Return the @f$ k @f$ parameter of the distribution.
+       * @brief Return the @f$k@f$ parameter of the distribution.
        */
       _IntType
       k() const
       { return _M_param.k(); }
 
       /**
-       * @brief Return the @f$ p @f$ parameter of the distribution.
+       * @brief Return the @f$p@f$ parameter of the distribution.
        */
       double
       p() const
@@ -3224,56 +4301,120 @@ namespace std
       max() const
       { return std::numeric_limits<result_type>::max(); }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
-       operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+        operator()(_UniformRandomNumberGenerator& __urng);
 
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
                   const param_type& __p);
 
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate_impl(__f, __t, __urng); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate_impl(__f, __t, __urng); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      /**
+       * @brief Return true if two negative binomial distributions have
+       *        the same parameters and the sequences that would be
+       *        generated are equal.
+       */
+      friend bool
+      operator==(const negative_binomial_distribution& __d1,
+                const negative_binomial_distribution& __d2)
+      { return __d1._M_param == __d2._M_param && __d1._M_gd == __d2._M_gd; }
+
+      /**
+       * @brief Inserts a %negative_binomial_distribution random
+       *        number distribution @p __x into the output stream @p __os.
+       *
+       * @param __os An output stream.
+       * @param __x  A %negative_binomial_distribution random number
+       *             distribution.
+       *
+       * @returns The output stream with the state of @p __x inserted or in
+       *          an error state.
+       */
+      template<typename _IntType1, typename _CharT, typename _Traits>
+       friend std::basic_ostream<_CharT, _Traits>&
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+                  const std::negative_binomial_distribution<_IntType1>& __x);
+
+      /**
+       * @brief Extracts a %negative_binomial_distribution random number
+       *        distribution @p __x from the input stream @p __is.
+       *
+       * @param __is An input stream.
+       * @param __x A %negative_binomial_distribution random number
+       *            generator engine.
+       *
+       * @returns The input stream with @p __x extracted or in an error state.
+       */
+      template<typename _IntType1, typename _CharT, typename _Traits>
+       friend std::basic_istream<_CharT, _Traits>&
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
+                  std::negative_binomial_distribution<_IntType1>& __x);
+
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng);
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       param_type _M_param;
+
+      std::gamma_distribution<double> _M_gd;
     };
 
   /**
-   * @brief Inserts a %negative_binomial_distribution random
-   *        number distribution @p __x into the output stream @p __os.
-   *
-   * @param __os An output stream.
-   * @param __x  A %negative_binomial_distribution random number
-   *             distribution.
-   *
-   * @returns The output stream with the state of @p __x inserted or in
-   *          an error state.
+   * @brief Return true if two negative binomial distributions are different.
    */
-  template<typename _IntType, typename _CharT, typename _Traits>
-    std::basic_ostream<_CharT, _Traits>&
-    operator<<(std::basic_ostream<_CharT, _Traits>&,
-              const std::negative_binomial_distribution<_IntType>&);
+  template<typename _IntType>
+    inline bool
+    operator!=(const std::negative_binomial_distribution<_IntType>& __d1,
+              const std::negative_binomial_distribution<_IntType>& __d2)
+    { return !(__d1 == __d2); }
 
-  /**
-   * @brief Extracts a %negative_binomial_distribution random number
-   *        distribution @p __x from the input stream @p __is.
-   *
-   * @param __is An input stream.
-   * @param __x A %negative_binomial_distribution random number
-   *            generator engine.
-   *
-   * @returns The input stream with @p __x extracted or in an error state.
-   */
-  template<typename _IntType, typename _CharT, typename _Traits>
-    std::basic_istream<_CharT, _Traits>&
-    operator>>(std::basic_istream<_CharT, _Traits>&,
-              std::negative_binomial_distribution<_IntType>&);
 
-  /* @} */ // group std_random_distributions_bernoulli
+  /* @} */ // group random_distributions_bernoulli
 
   /**
-   * @addtogroup std_random_distributions_poisson Poisson Distributions
-   * @ingroup std_random_distributions
+   * @addtogroup random_distributions_poisson Poisson Distributions
+   * @ingroup random_distributions
    * @{
    */
 
@@ -3281,13 +4422,14 @@ namespace std
    * @brief A discrete Poisson random number distribution.
    *
    * The formula for the Poisson probability density function is
-   * @f$ p(i|\mu) = \frac{\mu^i}{i!} e^{-\mu} @f$ where @f$ \mu @f$ is the
+   * @f$p(i|\mu) = \frac{\mu^i}{i!} e^{-\mu}@f$ where @f$\mu@f$ is the
    * parameter of the distribution.
    */
   template<typename _IntType = int>
     class poisson_distribution
     {
-      __glibcxx_class_requires(_IntType, _IntegerConcept)
+      static_assert(std::is_integral<_IntType>::value,
+                   "template argument not an integral type");
 
     public:
       /** The type of the range of the distribution. */
@@ -3310,6 +4452,10 @@ namespace std
        mean() const
        { return _M_mean; }
 
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_mean == __p2._M_mean; }
+
       private:
        // Hosts either log(mean) or the threshold of the simple method.
        void
@@ -3377,16 +4523,55 @@ namespace std
       max() const
       { return std::numeric_limits<result_type>::max(); }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+       { return this->operator()(__urng, _M_param); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
                   const param_type& __p);
 
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate(__f, __t, __urng, _M_param); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+       /**
+       * @brief Return true if two Poisson distributions have the same
+       *        parameters and the sequences that would be generated
+       *        are equal.
+       */
+      friend bool
+      operator==(const poisson_distribution& __d1,
+                const poisson_distribution& __d2)
+#ifdef _GLIBCXX_USE_C99_MATH_TR1
+      { return __d1._M_param == __d2._M_param && __d1._M_nd == __d2._M_nd; }
+#else
+      { return __d1._M_param == __d2._M_param; }
+#endif
+
       /**
        * @brief Inserts a %poisson_distribution random number distribution
        * @p __x into the output stream @p __os.
@@ -3399,8 +4584,8 @@ namespace std
        */
       template<typename _IntType1, typename _CharT, typename _Traits>
        friend std::basic_ostream<_CharT, _Traits>&
-       operator<<(std::basic_ostream<_CharT, _Traits>&,
-                  const std::poisson_distribution<_IntType1>&);
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+                  const std::poisson_distribution<_IntType1>& __x);
 
       /**
        * @brief Extracts a %poisson_distribution random number distribution
@@ -3414,248 +4599,110 @@ namespace std
        */
       template<typename _IntType1, typename _CharT, typename _Traits>
        friend std::basic_istream<_CharT, _Traits>&
-       operator>>(std::basic_istream<_CharT, _Traits>&,
-                  std::poisson_distribution<_IntType1>&);
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
+                  std::poisson_distribution<_IntType1>& __x);
 
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       param_type _M_param;
 
       // NB: Unused when _GLIBCXX_USE_C99_MATH_TR1 is undefined.
-      normal_distribution<double> _M_nd;
-    };
-
-  /**
-   * @brief An exponential continuous distribution for random numbers.
-   *
-   * The formula for the exponential probability density function is
-   * @f$ p(x|\lambda) = \lambda e^{-\lambda x} @f$.
-   *
-   * <table border=1 cellpadding=10 cellspacing=0>
-   * <caption align=top>Distribution Statistics</caption>
-   * <tr><td>Mean</td><td>@f$ \frac{1}{\lambda} @f$</td></tr>
-   * <tr><td>Median</td><td>@f$ \frac{\ln 2}{\lambda} @f$</td></tr>
-   * <tr><td>Mode</td><td>@f$ zero @f$</td></tr>
-   * <tr><td>Range</td><td>@f$[0, \infty]@f$</td></tr>
-   * <tr><td>Standard Deviation</td><td>@f$ \frac{1}{\lambda} @f$</td></tr>
-   * </table>
-   */
-  template<typename _RealType = double>
-    class exponential_distribution
-    {
-    public:
-      /** The type of the range of the distribution. */
-      typedef _RealType result_type;
-      /** Parameter type. */
-      struct param_type
-      {
-       typedef exponential_distribution<_RealType> distribution_type;
-
-       explicit
-       param_type(_RealType __lambda = _RealType(1))
-       : _M_lambda(__lambda)
-       {
-         _GLIBCXX_DEBUG_ASSERT(_M_lambda > _RealType(0));
-       }
-
-       _RealType
-       lambda() const
-       { return _M_lambda; }
-
-      private:
-       _RealType _M_lambda;
-      };
-
-    public:
-      /**
-       * @brief Constructs an exponential distribution with inverse scale
-       *        parameter @f$ \lambda @f$.
-       */
-      explicit
-      exponential_distribution(const result_type& __lambda = result_type(1))
-      : _M_param(__lambda)
-      { }
-
-      explicit
-      exponential_distribution(const param_type& __p)
-      : _M_param(__p)
-      { }
-
-      /**
-       * @brief Resets the distribution state.
-       *
-       * Has no effect on exponential distributions.
-       */
-      void
-      reset() { }
-
-      /**
-       * @brief Returns the inverse scale parameter of the distribution.
-       */
-      _RealType
-      lambda() const
-      { return _M_param.lambda(); }
-
-      /**
-       * @brief Returns the parameter set of the distribution.
-       */
-      param_type
-      param() const
-      { return _M_param; }
-
-      /**
-       * @brief Sets the parameter set of the distribution.
-       * @param __param The new parameter set of the distribution.
-       */
-      void
-      param(const param_type& __param)
-      { _M_param = __param; }
-
-      /**
-       * @brief Returns the greatest lower bound value of the distribution.
-       */
-      result_type
-      min() const
-      { return result_type(0); }
-
-      /**
-       * @brief Returns the least upper bound value of the distribution.
-       */
-      result_type
-      max() const
-      { return std::numeric_limits<result_type>::max(); }
-
-      template<typename _UniformRandomNumberGenerator>
-       result_type
-       operator()(_UniformRandomNumberGenerator& __urng)
-        { return this->operator()(__urng, this->param()); }
-
-      template<typename _UniformRandomNumberGenerator>
-       result_type
-       operator()(_UniformRandomNumberGenerator& __urng,
-                  const param_type& __p)
-       {
-         __detail::_Adaptor<_UniformRandomNumberGenerator, result_type>
-           __aurng(__urng);
-         return -std::log(__aurng()) / __p.lambda();
-       }
-
-    private:
-      param_type _M_param;
+      std::normal_distribution<double> _M_nd;
     };
 
-  /**
-   * @brief Inserts a %exponential_distribution random number distribution
-   * @p __x into the output stream @p __os.
-   *
-   * @param __os An output stream.
-   * @param __x  A %exponential_distribution random number distribution.
-   *
-   * @returns The output stream with the state of @p __x inserted or in
-   * an error state.
-   */
-  template<typename _RealType, typename _CharT, typename _Traits>
-    std::basic_ostream<_CharT, _Traits>&
-    operator<<(std::basic_ostream<_CharT, _Traits>&,
-              const std::exponential_distribution<_RealType>&);
-
-  /**
-   * @brief Extracts a %exponential_distribution random number distribution
-   * @p __x from the input stream @p __is.
-   *
-   * @param __is An input stream.
-   * @param __x A %exponential_distribution random number
-   *            generator engine.
-   *
-   * @returns The input stream with @p __x extracted or in an error state.
-   */
-  template<typename _RealType, typename _CharT, typename _Traits>
-    std::basic_istream<_CharT, _Traits>&
-    operator>>(std::basic_istream<_CharT, _Traits>&,
-              std::exponential_distribution<_RealType>&);
+  /**
+   * @brief Return true if two Poisson distributions are different.
+   */
+  template<typename _IntType>
+    inline bool
+    operator!=(const std::poisson_distribution<_IntType>& __d1,
+              const std::poisson_distribution<_IntType>& __d2)
+    { return !(__d1 == __d2); }
 
 
   /**
-   * @brief A gamma continuous distribution for random numbers.
+   * @brief An exponential continuous distribution for random numbers.
    *
-   * The formula for the gamma probability density function is
-   * @f$ p(x|\alpha,\beta) = \frac{1}{\beta\Gamma(\alpha)}
-   *                         (x/\beta)^{\alpha - 1} e^{-x/\beta} @f$.
+   * The formula for the exponential probability density function is
+   * @f$p(x|\lambda) = \lambda e^{-\lambda x}@f$.
+   *
+   * <table border=1 cellpadding=10 cellspacing=0>
+   * <caption align=top>Distribution Statistics</caption>
+   * <tr><td>Mean</td><td>@f$\frac{1}{\lambda}@f$</td></tr>
+   * <tr><td>Median</td><td>@f$\frac{\ln 2}{\lambda}@f$</td></tr>
+   * <tr><td>Mode</td><td>@f$zero@f$</td></tr>
+   * <tr><td>Range</td><td>@f$[0, \infty]@f$</td></tr>
+   * <tr><td>Standard Deviation</td><td>@f$\frac{1}{\lambda}@f$</td></tr>
+   * </table>
    */
   template<typename _RealType = double>
-    class gamma_distribution
+    class exponential_distribution
     {
+      static_assert(std::is_floating_point<_RealType>::value,
+                   "template argument not a floating point type");
+
     public:
       /** The type of the range of the distribution. */
       typedef _RealType result_type;
       /** Parameter type. */
       struct param_type
       {
-       typedef gamma_distribution<_RealType> distribution_type;
-       friend class gamma_distribution<_RealType>;
+       typedef exponential_distribution<_RealType> distribution_type;
 
        explicit
-       param_type(_RealType __alpha_val = _RealType(1),
-                  _RealType __beta_val = _RealType(1))
-       : _M_alpha(__alpha_val), _M_beta(__beta_val)
+       param_type(_RealType __lambda = _RealType(1))
+       : _M_lambda(__lambda)
        {
-         _GLIBCXX_DEBUG_ASSERT(_M_alpha > _RealType(0));
-         _M_initialize();
+         _GLIBCXX_DEBUG_ASSERT(_M_lambda > _RealType(0));
        }
 
        _RealType
-       alpha() const
-       { return _M_alpha; }
+       lambda() const
+       { return _M_lambda; }
 
-       _RealType
-       beta() const
-       { return _M_beta; }
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_lambda == __p2._M_lambda; }
 
       private:
-       void
-       _M_initialize();
-
-       _RealType _M_alpha;
-       _RealType _M_beta;
-
-       _RealType _M_malpha, _M_a2;
+       _RealType _M_lambda;
       };
 
     public:
       /**
-       * @brief Constructs a gamma distribution with parameters
-       * @f$ \alpha @f$ and @f$ \beta @f$.
+       * @brief Constructs an exponential distribution with inverse scale
+       *        parameter @f$\lambda@f$.
        */
       explicit
-      gamma_distribution(_RealType __alpha_val = _RealType(1),
-                        _RealType __beta_val = _RealType(1))
-      : _M_param(__alpha_val, __beta_val), _M_nd()
+      exponential_distribution(const result_type& __lambda = result_type(1))
+      : _M_param(__lambda)
       { }
 
       explicit
-      gamma_distribution(const param_type& __p)
-      : _M_param(__p), _M_nd()
+      exponential_distribution(const param_type& __p)
+      : _M_param(__p)
       { }
 
       /**
        * @brief Resets the distribution state.
+       *
+       * Has no effect on exponential distributions.
        */
       void
-      reset()
-      { _M_nd.reset(); }
-
-      /**
-       * @brief Returns the @f$ \alpha @f$ of the distribution.
-       */
-      _RealType
-      alpha() const
-      { return _M_param.alpha(); }
+      reset() { }
 
       /**
-       * @brief Returns the @f$ \beta @f$ of the distribution.
+       * @brief Returns the inverse scale parameter of the distribution.
        */
       _RealType
-      beta() const
-      { return _M_param.beta(); }
+      lambda() const
+      { return _M_param.lambda(); }
 
       /**
        * @brief Returns the parameter set of the distribution.
@@ -3686,62 +4733,122 @@ namespace std
       max() const
       { return std::numeric_limits<result_type>::max(); }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+        { return this->operator()(__urng, _M_param); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
-                  const param_type& __p);
+                  const param_type& __p)
+       {
+         __detail::_Adaptor<_UniformRandomNumberGenerator, result_type>
+           __aurng(__urng);
+         return -std::log(result_type(1) - __aurng()) / __p.lambda();
+       }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate(__f, __t, __urng, _M_param); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      /**
+       * @brief Return true if two exponential distributions have the same
+       *        parameters.
+       */
+      friend bool
+      operator==(const exponential_distribution& __d1,
+                const exponential_distribution& __d2)
+      { return __d1._M_param == __d2._M_param; }
 
     private:
-      param_type _M_param;
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
 
-      normal_distribution<result_type> _M_nd;
+      param_type _M_param;
     };
 
   /**
-   * @brief Inserts a %gamma_distribution random number distribution
+   * @brief Return true if two exponential distributions have different
+   *        parameters.
+   */
+  template<typename _RealType>
+    inline bool
+    operator!=(const std::exponential_distribution<_RealType>& __d1,
+              const std::exponential_distribution<_RealType>& __d2)
+    { return !(__d1 == __d2); }
+
+  /**
+   * @brief Inserts a %exponential_distribution random number distribution
    * @p __x into the output stream @p __os.
    *
    * @param __os An output stream.
-   * @param __x  A %gamma_distribution random number distribution.
+   * @param __x  A %exponential_distribution random number distribution.
    *
    * @returns The output stream with the state of @p __x inserted or in
    * an error state.
    */
   template<typename _RealType, typename _CharT, typename _Traits>
     std::basic_ostream<_CharT, _Traits>&
-    operator<<(std::basic_ostream<_CharT, _Traits>&,
-              const std::gamma_distribution<_RealType>&);
+    operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+              const std::exponential_distribution<_RealType>& __x);
 
   /**
-   * @brief Extracts a %gamma_distribution random number distribution
+   * @brief Extracts a %exponential_distribution random number distribution
    * @p __x from the input stream @p __is.
    *
    * @param __is An input stream.
-   * @param __x  A %gamma_distribution random number generator engine.
+   * @param __x A %exponential_distribution random number
+   *            generator engine.
    *
    * @returns The input stream with @p __x extracted or in an error state.
    */
   template<typename _RealType, typename _CharT, typename _Traits>
     std::basic_istream<_CharT, _Traits>&
-    operator>>(std::basic_istream<_CharT, _Traits>&,
-              std::gamma_distribution<_RealType>&);
+    operator>>(std::basic_istream<_CharT, _Traits>& __is,
+              std::exponential_distribution<_RealType>& __x);
 
 
   /**
    * @brief A weibull_distribution random number distribution.
    *
-   * The formula for the normal probability density function is
-   * @f$ p(x|\alpha,\beta) = \frac{a}{b} (frac{x}{b})^{a-1}
-   *                         \exp{(-(frac{x}{b})^a)} @f$.
+   * The formula for the normal probability density function is:
+   * @f[
+   *     p(x|\alpha,\beta) = \frac{\alpha}{\beta} (\frac{x}{\beta})^{\alpha-1}
+   *                         \exp{(-(\frac{x}{\beta})^\alpha)} 
+   * @f]
    */
   template<typename _RealType = double>
     class weibull_distribution
     {
+      static_assert(std::is_floating_point<_RealType>::value,
+                   "template argument not a floating point type");
+
     public:
       /** The type of the range of the distribution. */
       typedef _RealType result_type;
@@ -3764,6 +4871,10 @@ namespace std
        b() const
        { return _M_b; }
 
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_a == __p2._M_a && __p1._M_b == __p2._M_b; }
+
       private:
        _RealType _M_a;
        _RealType _M_b;
@@ -3788,14 +4899,14 @@ namespace std
       { }
 
       /**
-       * @brief Return the @f$ a @f$ parameter of the distribution.
+       * @brief Return the @f$a@f$ parameter of the distribution.
        */
       _RealType
       a() const
       { return _M_param.a(); }
 
       /**
-       * @brief Return the @f$ b @f$ parameter of the distribution.
+       * @brief Return the @f$b@f$ parameter of the distribution.
        */
       _RealType
       b() const
@@ -3830,20 +4941,71 @@ namespace std
       max() const
       { return std::numeric_limits<result_type>::max(); }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+       { return this->operator()(__urng, _M_param); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
                   const param_type& __p);
 
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate(__f, __t, __urng, _M_param); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      /**
+       * @brief Return true if two Weibull distributions have the same
+       *        parameters.
+       */
+      friend bool
+      operator==(const weibull_distribution& __d1,
+                const weibull_distribution& __d2)
+      { return __d1._M_param == __d2._M_param; }
+
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       param_type _M_param;
     };
 
+   /**
+    * @brief Return true if two Weibull distributions have different
+    *        parameters.
+    */
+  template<typename _RealType>
+    inline bool
+    operator!=(const std::weibull_distribution<_RealType>& __d1,
+              const std::weibull_distribution<_RealType>& __d2)
+    { return !(__d1 == __d2); }
+
   /**
    * @brief Inserts a %weibull_distribution random number distribution
    * @p __x into the output stream @p __os.
@@ -3856,8 +5018,8 @@ namespace std
    */
   template<typename _RealType, typename _CharT, typename _Traits>
     std::basic_ostream<_CharT, _Traits>&
-    operator<<(std::basic_ostream<_CharT, _Traits>&,
-              const std::weibull_distribution<_RealType>&);
+    operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+              const std::weibull_distribution<_RealType>& __x);
 
   /**
    * @brief Extracts a %weibull_distribution random number distribution
@@ -3871,20 +5033,25 @@ namespace std
    */
   template<typename _RealType, typename _CharT, typename _Traits>
     std::basic_istream<_CharT, _Traits>&
-    operator>>(std::basic_istream<_CharT, _Traits>&,
-              std::weibull_distribution<_RealType>&);
+    operator>>(std::basic_istream<_CharT, _Traits>& __is,
+              std::weibull_distribution<_RealType>& __x);
 
 
   /**
    * @brief A extreme_value_distribution random number distribution.
    *
    * The formula for the normal probability mass function is
-   * @f$ p(x|a,b) = \frac{1}{b}
-   *                \exp( \frac{a-x}{b} - \exp(\frac{a-x}{b})) @f$
+   * @f[
+   *     p(x|a,b) = \frac{1}{b}
+   *                \exp( \frac{a-x}{b} - \exp(\frac{a-x}{b})) 
+   * @f]
    */
   template<typename _RealType = double>
     class extreme_value_distribution
     {
+      static_assert(std::is_floating_point<_RealType>::value,
+                   "template argument not a floating point type");
+
     public:
       /** The type of the range of the distribution. */
       typedef _RealType result_type;
@@ -3907,6 +5074,10 @@ namespace std
        b() const
        { return _M_b; }
 
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_a == __p2._M_a && __p1._M_b == __p2._M_b; }
+
       private:
        _RealType _M_a;
        _RealType _M_b;
@@ -3931,14 +5102,14 @@ namespace std
       { }
 
       /**
-       * @brief Return the @f$ a @f$ parameter of the distribution.
+       * @brief Return the @f$a@f$ parameter of the distribution.
        */
       _RealType
       a() const
       { return _M_param.a(); }
 
       /**
-       * @brief Return the @f$ b @f$ parameter of the distribution.
+       * @brief Return the @f$b@f$ parameter of the distribution.
        */
       _RealType
       b() const
@@ -3964,7 +5135,7 @@ namespace std
        */
       result_type
       min() const
-      { return std::numeric_limits<result_type>::min(); }
+      { return std::numeric_limits<result_type>::lowest(); }
 
       /**
        * @brief Returns the least upper bound value of the distribution.
@@ -3973,20 +5144,71 @@ namespace std
       max() const
       { return std::numeric_limits<result_type>::max(); }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+       { return this->operator()(__urng, _M_param); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
                   const param_type& __p);
 
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate(__f, __t, __urng, _M_param); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      /**
+       * @brief Return true if two extreme value distributions have the same
+       *        parameters.
+       */
+      friend bool
+      operator==(const extreme_value_distribution& __d1,
+                const extreme_value_distribution& __d2)
+      { return __d1._M_param == __d2._M_param; }
+
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       param_type _M_param;
     };
 
+  /**
+    * @brief Return true if two extreme value distributions have different
+    *        parameters.
+   */
+  template<typename _RealType>
+    inline bool
+    operator!=(const std::extreme_value_distribution<_RealType>& __d1,
+              const std::extreme_value_distribution<_RealType>& __d2)
+    { return !(__d1 == __d2); }
+
   /**
    * @brief Inserts a %extreme_value_distribution random number distribution
    * @p __x into the output stream @p __os.
@@ -3999,8 +5221,8 @@ namespace std
    */
   template<typename _RealType, typename _CharT, typename _Traits>
     std::basic_ostream<_CharT, _Traits>&
-    operator<<(std::basic_ostream<_CharT, _Traits>&,
-              const std::extreme_value_distribution<_RealType>&);
+    operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+              const std::extreme_value_distribution<_RealType>& __x);
 
   /**
    * @brief Extracts a %extreme_value_distribution random number
@@ -4014,8 +5236,8 @@ namespace std
    */
   template<typename _RealType, typename _CharT, typename _Traits>
     std::basic_istream<_CharT, _Traits>&
-    operator>>(std::basic_istream<_CharT, _Traits>&,
-              std::extreme_value_distribution<_RealType>&);
+    operator>>(std::basic_istream<_CharT, _Traits>& __is,
+              std::extreme_value_distribution<_RealType>& __x);
 
 
   /**
@@ -4027,7 +5249,8 @@ namespace std
   template<typename _IntType = int>
     class discrete_distribution
     {
-      __glibcxx_class_requires(_IntType, _IntegerConcept)
+      static_assert(std::is_integral<_IntType>::value,
+                   "template argument not an integral type");
 
     public:
       /** The type of the range of the distribution. */
@@ -4040,7 +5263,7 @@ namespace std
 
        param_type()
        : _M_prob(), _M_cp()
-       { _M_initialize(); }
+       { }
 
        template<typename _InputIterator>
          param_type(_InputIterator __wbegin,
@@ -4056,9 +5279,17 @@ namespace std
          param_type(size_t __nw, double __xmin, double __xmax,
                     _Func __fw);
 
+       // See: http://cpp-next.com/archive/2010/10/implicit-move-must-go/
+       param_type(const param_type&) = default;
+       param_type& operator=(const param_type&) = default;
+
        std::vector<double>
        probabilities() const
-       { return _M_prob; }
+       { return _M_prob.empty() ? std::vector<double>(1, 1.0) : _M_prob; }
+
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_prob == __p2._M_prob; }
 
       private:
        void
@@ -4078,8 +5309,8 @@ namespace std
        : _M_param(__wbegin, __wend)
        { }
 
-      discrete_distribution(initializer_list<double> __wil)
-      : _M_param(__wil)
+      discrete_distribution(initializer_list<double> __wl)
+      : _M_param(__wl)
       { }
 
       template<typename _Func>
@@ -4105,7 +5336,10 @@ namespace std
        */
       std::vector<double>
       probabilities() const
-      { return _M_param.probabilities(); }
+      {
+       return _M_param._M_prob.empty()
+         ? std::vector<double>(1, 1.0) : _M_param._M_prob;
+      }
 
       /**
        * @brief Returns the parameter set of the distribution.
@@ -4134,18 +5368,55 @@ namespace std
        */
       result_type
       max() const
-      { return this->_M_param._M_prob.size() - 1; }
+      {
+       return _M_param._M_prob.empty()
+         ? result_type(0) : result_type(_M_param._M_prob.size() - 1);
+      }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+       { return this->operator()(__urng, _M_param); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
                   const param_type& __p);
 
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate(__f, __t, __urng, _M_param); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      /**
+       * @brief Return true if two discrete distributions have the same
+       *        parameters.
+       */
+      friend bool
+      operator==(const discrete_distribution& __d1,
+                const discrete_distribution& __d2)
+      { return __d1._M_param == __d2._M_param; }
+
       /**
        * @brief Inserts a %discrete_distribution random number distribution
        * @p __x into the output stream @p __os.
@@ -4158,8 +5429,8 @@ namespace std
        */
       template<typename _IntType1, typename _CharT, typename _Traits>
        friend std::basic_ostream<_CharT, _Traits>&
-       operator<<(std::basic_ostream<_CharT, _Traits>&,
-                  const std::discrete_distribution<_IntType1>&);
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+                  const std::discrete_distribution<_IntType1>& __x);
 
       /**
        * @brief Extracts a %discrete_distribution random number distribution
@@ -4174,13 +5445,30 @@ namespace std
        */
       template<typename _IntType1, typename _CharT, typename _Traits>
        friend std::basic_istream<_CharT, _Traits>&
-       operator>>(std::basic_istream<_CharT, _Traits>&,
-                  std::discrete_distribution<_IntType1>&);
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
+                  std::discrete_distribution<_IntType1>& __x);
 
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       param_type _M_param;
     };
 
+  /**
+    * @brief Return true if two discrete distributions have different
+    *        parameters.
+    */
+  template<typename _IntType>
+    inline bool
+    operator!=(const std::discrete_distribution<_IntType>& __d1,
+              const std::discrete_distribution<_IntType>& __d2)
+    { return !(__d1 == __d2); }
+
 
   /**
    * @brief A piecewise_constant_distribution random number distribution.
@@ -4191,6 +5479,9 @@ namespace std
   template<typename _RealType = double>
     class piecewise_constant_distribution
     {
+      static_assert(std::is_floating_point<_RealType>::value,
+                   "template argument not a floating point type");
+
     public:
       /** The type of the range of the distribution. */
       typedef _RealType result_type;
@@ -4202,7 +5493,7 @@ namespace std
 
        param_type()
        : _M_int(), _M_den(), _M_cp()
-       { _M_initialize(); }
+       { }
 
        template<typename _InputIteratorB, typename _InputIteratorW>
          param_type(_InputIteratorB __bfirst,
@@ -4210,19 +5501,36 @@ namespace std
                     _InputIteratorW __wbegin);
 
        template<typename _Func>
-         param_type(initializer_list<_RealType> __bil, _Func __fw);
+         param_type(initializer_list<_RealType> __bi, _Func __fw);
 
        template<typename _Func>
          param_type(size_t __nw, _RealType __xmin, _RealType __xmax,
                     _Func __fw);
 
+       // See: http://cpp-next.com/archive/2010/10/implicit-move-must-go/
+       param_type(const param_type&) = default;
+       param_type& operator=(const param_type&) = default;
+
        std::vector<_RealType>
        intervals() const
-       { return _M_int; }
+       {
+         if (_M_int.empty())
+           {
+             std::vector<_RealType> __tmp(2);
+             __tmp[1] = _RealType(1);
+             return __tmp;
+           }
+         else
+           return _M_int;
+       }
 
        std::vector<double>
        densities() const
-       { return _M_den; }
+       { return _M_den.empty() ? std::vector<double>(1, 1.0) : _M_den; }
+
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return __p1._M_int == __p2._M_int && __p1._M_den == __p2._M_den; }
 
       private:
        void
@@ -4246,9 +5554,9 @@ namespace std
        { }
 
       template<typename _Func>
-       piecewise_constant_distribution(initializer_list<_RealType> __bil,
+       piecewise_constant_distribution(initializer_list<_RealType> __bl,
                                        _Func __fw)
-       : _M_param(__bil, __fw)
+       : _M_param(__bl, __fw)
        { }
 
       template<typename _Func>
@@ -4275,14 +5583,26 @@ namespace std
        */
       std::vector<_RealType>
       intervals() const
-      { return _M_param.intervals(); }
+      {
+       if (_M_param._M_int.empty())
+         {
+           std::vector<_RealType> __tmp(2);
+           __tmp[1] = _RealType(1);
+           return __tmp;
+         }
+       else
+         return _M_param._M_int;
+      }
 
       /**
        * @brief Returns a vector of the probability densities.
        */
       std::vector<double>
       densities() const
-      { return _M_param.densities(); }
+      {
+       return _M_param._M_den.empty()
+         ? std::vector<double>(1, 1.0) : _M_param._M_den;
+      }
 
       /**
        * @brief Returns the parameter set of the distribution.
@@ -4304,31 +5624,71 @@ namespace std
        */
       result_type
       min() const
-      { return this->_M_param._M_int.front(); }
+      {
+       return _M_param._M_int.empty()
+         ? result_type(0) : _M_param._M_int.front();
+      }
 
       /**
        * @brief Returns the least upper bound value of the distribution.
        */
       result_type
       max() const
-      { return this->_M_param._M_int.back(); }
+      {
+       return _M_param._M_int.empty()
+         ? result_type(1) : _M_param._M_int.back();
+      }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+       { return this->operator()(__urng, _M_param); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
                   const param_type& __p);
 
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate(__f, __t, __urng, _M_param); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
       /**
-       * @brief Inserts a %piecewise_constan_distribution random
+       * @brief Return true if two piecewise constant distributions have the
+       *        same parameters.
+       */
+      friend bool
+      operator==(const piecewise_constant_distribution& __d1,
+                const piecewise_constant_distribution& __d2)
+      { return __d1._M_param == __d2._M_param; }
+
+      /**
+       * @brief Inserts a %piecewise_constant_distribution random
        *        number distribution @p __x into the output stream @p __os.
        *
        * @param __os An output stream.
-       * @param __x  A %piecewise_constan_distribution random number
+       * @param __x  A %piecewise_constant_distribution random number
        *             distribution.
        *
        * @returns The output stream with the state of @p __x inserted or in
@@ -4336,15 +5696,15 @@ namespace std
        */
       template<typename _RealType1, typename _CharT, typename _Traits>
        friend std::basic_ostream<_CharT, _Traits>&
-       operator<<(std::basic_ostream<_CharT, _Traits>&,
-                  const std::piecewise_constant_distribution<_RealType1>&);
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+                  const std::piecewise_constant_distribution<_RealType1>& __x);
 
       /**
-       * @brief Extracts a %piecewise_constan_distribution random
+       * @brief Extracts a %piecewise_constant_distribution random
        *        number distribution @p __x from the input stream @p __is.
        *
        * @param __is An input stream.
-       * @param __x A %piecewise_constan_distribution random number
+       * @param __x A %piecewise_constant_distribution random number
        *            generator engine.
        *
        * @returns The input stream with @p __x extracted or in an error
@@ -4352,13 +5712,30 @@ namespace std
        */
       template<typename _RealType1, typename _CharT, typename _Traits>
        friend std::basic_istream<_CharT, _Traits>&
-       operator>>(std::basic_istream<_CharT, _Traits>&,
-                  std::piecewise_constant_distribution<_RealType1>&);
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
+                  std::piecewise_constant_distribution<_RealType1>& __x);
 
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       param_type _M_param;
     };
 
+  /**
+    * @brief Return true if two piecewise constant distributions have 
+    *        different parameters.
+   */
+  template<typename _RealType>
+    inline bool
+    operator!=(const std::piecewise_constant_distribution<_RealType>& __d1,
+              const std::piecewise_constant_distribution<_RealType>& __d2)
+    { return !(__d1 == __d2); }
+
 
   /**
    * @brief A piecewise_linear_distribution random number distribution.
@@ -4369,6 +5746,9 @@ namespace std
   template<typename _RealType = double>
     class piecewise_linear_distribution
     {
+      static_assert(std::is_floating_point<_RealType>::value,
+                   "template argument not a floating point type");
+
     public:
       /** The type of the range of the distribution. */
       typedef _RealType result_type;
@@ -4378,7 +5758,9 @@ namespace std
        typedef piecewise_linear_distribution<_RealType> distribution_type;
        friend class piecewise_linear_distribution<_RealType>;
 
-       param_type();
+       param_type()
+       : _M_int(), _M_den(), _M_cp(), _M_m()
+       { }
 
        template<typename _InputIteratorB, typename _InputIteratorW>
          param_type(_InputIteratorB __bfirst,
@@ -4386,19 +5768,37 @@ namespace std
                     _InputIteratorW __wbegin);
 
        template<typename _Func>
-         param_type(initializer_list<_RealType> __bil, _Func __fw);
+         param_type(initializer_list<_RealType> __bl, _Func __fw);
 
        template<typename _Func>
          param_type(size_t __nw, _RealType __xmin, _RealType __xmax,
                     _Func __fw);
 
+       // See: http://cpp-next.com/archive/2010/10/implicit-move-must-go/
+       param_type(const param_type&) = default;
+       param_type& operator=(const param_type&) = default;
+
        std::vector<_RealType>
        intervals() const
-       { return _M_int; }
+       {
+         if (_M_int.empty())
+           {
+             std::vector<_RealType> __tmp(2);
+             __tmp[1] = _RealType(1);
+             return __tmp;
+           }
+         else
+           return _M_int;
+       }
 
        std::vector<double>
        densities() const
-       { return _M_den; }
+       { return _M_den.empty() ? std::vector<double>(2, 1.0) : _M_den; }
+
+       friend bool
+       operator==(const param_type& __p1, const param_type& __p2)
+       { return (__p1._M_int == __p2._M_int
+                 && __p1._M_den == __p2._M_den); }
 
       private:
        void
@@ -4423,9 +5823,9 @@ namespace std
        { }
 
       template<typename _Func>
-       piecewise_linear_distribution(initializer_list<_RealType> __bil,
+       piecewise_linear_distribution(initializer_list<_RealType> __bl,
                                      _Func __fw)
-       : _M_param(__bil, __fw)
+       : _M_param(__bl, __fw)
        { }
 
       template<typename _Func>
@@ -4452,7 +5852,16 @@ namespace std
        */
       std::vector<_RealType>
       intervals() const
-      { return _M_param.intervals(); }
+      {
+       if (_M_param._M_int.empty())
+         {
+           std::vector<_RealType> __tmp(2);
+           __tmp[1] = _RealType(1);
+           return __tmp;
+         }
+       else
+         return _M_param._M_int;
+      }
 
       /**
        * @brief Return a vector of the probability densities of the
@@ -4460,7 +5869,10 @@ namespace std
        */
       std::vector<double>
       densities() const
-      { return _M_param.densities(); }
+      {
+       return _M_param._M_den.empty()
+         ? std::vector<double>(2, 1.0) : _M_param._M_den;
+      }
 
       /**
        * @brief Returns the parameter set of the distribution.
@@ -4482,25 +5894,65 @@ namespace std
        */
       result_type
       min() const
-      { return this->_M_param._M_int.front(); }
+      {
+       return _M_param._M_int.empty()
+         ? result_type(0) : _M_param._M_int.front();
+      }
 
       /**
        * @brief Returns the least upper bound value of the distribution.
        */
       result_type
       max() const
-      { return this->_M_param._M_int.back(); }
+      {
+       return _M_param._M_int.empty()
+         ? result_type(1) : _M_param._M_int.back();
+      }
 
+      /**
+       * @brief Generating functions.
+       */
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng)
-       { return this->operator()(__urng, this->param()); }
+       { return this->operator()(__urng, _M_param); }
 
       template<typename _UniformRandomNumberGenerator>
        result_type
        operator()(_UniformRandomNumberGenerator& __urng,
                   const param_type& __p);
 
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng)
+       { this->__generate(__f, __t, __urng, _M_param); }
+
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate(_ForwardIterator __f, _ForwardIterator __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      template<typename _UniformRandomNumberGenerator>
+       void
+       __generate(result_type* __f, result_type* __t,
+                  _UniformRandomNumberGenerator& __urng,
+                  const param_type& __p)
+       { this->__generate_impl(__f, __t, __urng, __p); }
+
+      /**
+       * @brief Return true if two piecewise linear distributions have the
+       *        same parameters.
+       */
+      friend bool
+      operator==(const piecewise_linear_distribution& __d1,
+                const piecewise_linear_distribution& __d2)
+      { return __d1._M_param == __d2._M_param; }
+
       /**
        * @brief Inserts a %piecewise_linear_distribution random number
        *        distribution @p __x into the output stream @p __os.
@@ -4514,8 +5966,8 @@ namespace std
        */
       template<typename _RealType1, typename _CharT, typename _Traits>
        friend std::basic_ostream<_CharT, _Traits>&
-       operator<<(std::basic_ostream<_CharT, _Traits>&,
-                  const std::piecewise_linear_distribution<_RealType1>&);
+       operator<<(std::basic_ostream<_CharT, _Traits>& __os,
+                  const std::piecewise_linear_distribution<_RealType1>& __x);
 
       /**
        * @brief Extracts a %piecewise_linear_distribution random number
@@ -4530,21 +5982,38 @@ namespace std
        */
       template<typename _RealType1, typename _CharT, typename _Traits>
        friend std::basic_istream<_CharT, _Traits>&
-       operator>>(std::basic_istream<_CharT, _Traits>&,
-                  std::piecewise_linear_distribution<_RealType1>&);
+       operator>>(std::basic_istream<_CharT, _Traits>& __is,
+                  std::piecewise_linear_distribution<_RealType1>& __x);
 
     private:
+      template<typename _ForwardIterator,
+              typename _UniformRandomNumberGenerator>
+       void
+       __generate_impl(_ForwardIterator __f, _ForwardIterator __t,
+                       _UniformRandomNumberGenerator& __urng,
+                       const param_type& __p);
+
       param_type _M_param;
     };
 
+  /**
+    * @brief Return true if two piecewise linear distributions have
+    *        different parameters.
+   */
+  template<typename _RealType>
+    inline bool
+    operator!=(const std::piecewise_linear_distribution<_RealType>& __d1,
+              const std::piecewise_linear_distribution<_RealType>& __d2)
+    { return !(__d1 == __d2); }
 
-  /* @} */ // group std_random_distributions_poisson
 
-  /* @} */ // group std_random_distributions
+  /* @} */ // group random_distributions_poisson
+
+  /* @} */ // group random_distributions
 
   /**
-   * @addtogroup std_random_utilities Random Number Utilities
-   * @ingroup std_random
+   * @addtogroup random_utilities Random Number Utilities
+   * @ingroup random
    * @{
    */
 
@@ -4589,9 +6058,11 @@ namespace std
     std::vector<result_type> _M_v;
   };
 
-  /* @} */ // group std_random_utilities
+  /* @} */ // group random_utilities
 
-  /* @} */ // group std_random
+  /* @} */ // group random
 
-}
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
 
+#endif