add note that sinpi/cospi are actually easier than sin/cos to implement in hardware

diff --git a/openpower/transcendentals.mdwn b/openpower/transcendentals.mdwn
index 4d89ad7b23610263f1253f8bfc97201983e77bfb..cf68d6888bd6eada608f7909d9ec17a48a83a2e6 100644 (file)
--- a/openpower/transcendentals.mdwn
+++ b/openpower/transcendentals.mdwn
@@ -372,6 +372,8 @@ Ztrignpi are the basic trigonometric functions through which all others
 could be synthesised, and they are typically the base trigonometrics
 provided by GPUs for 3D, warranting their own subset.
 
+(programmerjake: actually, all other GPU ISAs mentioned in this document have sinpi/cospi or equivalent, and often not sin/cos, because sinpi/cospi are actually *waay* easier to implement because range reduction is simply a bitwise mask, whereas for sin/cos range reduction is a full division by pi)
+
 In the case of the Ztrigpi subset, these are commonly used in for loops
 with a power of two number of subdivisions, and the cost of multiplying
 by PI inside each loop (or cumulative addition, resulting in cumulative