libgo/go/math/huge_test.go

   1 // Copyright 2018 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // Disabled for s390x because it uses assembly routines that are not
   6 // accurate for huge arguments.
   7
   8 // +build !s390x
   9
  10 package math_test
  11
  12 import (
  13         . "math"
  14         "testing"
  15 )
  16
  17 // Inputs to test trig_reduce
  18 var trigHuge = []float64{
  19         1 << 120,
  20         1 << 240,
  21         1 << 480,
  22         1234567891234567 << 180,
  23         1234567891234567 << 300,
  24         MaxFloat64,
  25 }
  26
  27 // Results for trigHuge[i] calculated with https://github.com/robpike/ivy
  28 // using 4096 bits of working precision.   Values requiring less than
  29 // 102 decimal digits (1 << 120, 1 << 240, 1 << 480, 1234567891234567 << 180)
  30 // were confirmed via https://keisan.casio.com/
  31 var cosHuge = []float64{
  32         -0.92587902285483787,
  33         0.93601042593353793,
  34         -0.28282777640193788,
  35         -0.14616431394103619,
  36         -0.79456058210671406,
  37         -0.99998768942655994,
  38 }
  39
  40 var sinHuge = []float64{
  41         0.37782010936075202,
  42         -0.35197227524865778,
  43         0.95917070894368716,
  44         0.98926032637023618,
  45         -0.60718488235646949,
  46         0.00496195478918406,
  47 }
  48
  49 var tanHuge = []float64{
  50         -0.40806638884180424,
  51         -0.37603456702698076,
  52         -3.39135965054779932,
  53         -6.76813854009065030,
  54         0.76417695016604922,
  55         -0.00496201587444489,
  56 }
  57
  58 // Check that trig values of huge angles return accurate results.
  59 // This confirms that argument reduction works for very large values
  60 // up to MaxFloat64.
  61 func TestHugeCos(t *testing.T) {
  62         for i := 0; i < len(trigHuge); i++ {
  63                 f1 := cosHuge[i]
  64                 f2 := Cos(trigHuge[i])
  65                 if !close(f1, f2) {
  66                         t.Errorf("Cos(%g) = %g, want %g", trigHuge[i], f2, f1)
  67                 }
  68         }
  69 }
  70
  71 func TestHugeSin(t *testing.T) {
  72         for i := 0; i < len(trigHuge); i++ {
  73                 f1 := sinHuge[i]
  74                 f2 := Sin(trigHuge[i])
  75                 if !close(f1, f2) {
  76                         t.Errorf("Sin(%g) = %g, want %g", trigHuge[i], f2, f1)
  77                 }
  78         }
  79 }
  80
  81 func TestHugeSinCos(t *testing.T) {
  82         for i := 0; i < len(trigHuge); i++ {
  83                 f1, g1 := sinHuge[i], cosHuge[i]
  84                 f2, g2 := Sincos(trigHuge[i])
  85                 if !close(f1, f2) || !close(g1, g2) {
  86                         t.Errorf("Sincos(%g) = %g, %g, want %g, %g", trigHuge[i], f2, g2, f1, g1)
  87                 }
  88         }
  89 }
  90
  91 func TestHugeTan(t *testing.T) {
  92         for i := 0; i < len(trigHuge); i++ {
  93                 f1 := tanHuge[i]
  94                 f2 := Tan(trigHuge[i])
  95                 if !close(f1, f2) {
  96                         t.Errorf("Tan(%g) = %g, want %g", trigHuge[i], f2, f1)
  97                 }
  98         }
  99 }