Mesa (master): gallivm: Simplify/reorder minimax helper.
Jose Fonseca
jrfonseca at kemper.freedesktop.org
Tue Apr 3 08:33:25 UTC 2012
Module: Mesa
Branch: master
Commit: d312b224b6759fd9b206d4c19450f6a4dfe53311
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=d312b224b6759fd9b206d4c19450f6a4dfe53311
Author: José Fonseca <jfonseca at vmware.com>
Date: Tue Apr 3 09:10:53 2012 +0100
gallivm: Simplify/reorder minimax helper.
---
src/gallium/auxiliary/gallivm/f.cpp | 25 +++++++++++++++----------
1 files changed, 15 insertions(+), 10 deletions(-)
diff --git a/src/gallium/auxiliary/gallivm/f.cpp b/src/gallium/auxiliary/gallivm/f.cpp
index 6b9c35b..7cb50f1 100644
--- a/src/gallium/auxiliary/gallivm/f.cpp
+++ b/src/gallium/auxiliary/gallivm/f.cpp
@@ -31,20 +31,20 @@
*
* ./minimax
*
- * - For example, to compute log2 5th order polynomial between [1, 2] do:
+ * - For example, to compute exp2 5th order polynomial between [0, 1] do:
*
* variant 0
- * range 1 2
+ * range 0 1
* order 5 0
* step 200
* info
*
* and take the coefficients from the P = { ... } array.
*
- * - To compute exp2 5th order polynomial between [0, 1] do:
+ * - To compute log2 5th order polynomial between [1, 2] do:
*
* variant 1
- * range 0 1
+ * range 1 2
* order 5 0
* step 200
* info
@@ -59,20 +59,25 @@
#include <cmath>
+boost::math::ntl::RR exp2(const boost::math::ntl::RR& x)
+{
+ return exp(x*log(2.0));
+}
+
+boost::math::ntl::RR log2(const boost::math::ntl::RR& x)
+{
+ return log(x)/log(2.0);
+}
boost::math::ntl::RR f(const boost::math::ntl::RR& x, int variant)
{
- static const boost::math::ntl::RR tiny = boost::math::tools::min_value<boost::math::ntl::RR>() * 64;
-
switch(variant)
{
case 0:
- // log2(x)/(x - 1)
- return log(x)/log(2.0)/(x - 1.0);
+ return exp2(x);
case 1:
- // exp2(x)
- return exp(x*log(2.0));
+ return log2(x)/(x - 1.0);
}
return 0;
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