From aba5e333d4bde2710d9e91dfbc660bd881aef1f7 Mon Sep 17 00:00:00 2001 From: Carlos O'Donell Date: Thu, 11 Apr 2013 08:52:18 -0400 Subject: libm-test.inc: Fix tests where cos(PI/2) != 0. The value of PI is never exactly PI in any floating point representation, and the value of PI/2 is never PI/2. It is wrong to expect cos(M_PI_2l) to return 0, instead it will return an answer that is non-zero because M_PI_2l doesn't round to exactly PI/2 in the type used. That is to say that the correct answer is to do the following: * Take PI or PI/2. * Round to the floating point representation. * Take the rounded value and compute an infinite precision cos or sin. * Use the rounded result of the infinite precision cos or sin as the answer to the test. I used printf to do the type rounding, and Wolfram's Alpha to do the infinite precision cos calculations. The following changes bring x86-64 and x86 to 1/2 ulp for two tests. It shows that the x86 cos implementation is quite good, and that our test are flawed. Unfortunately given that the rounding errors are type dependent we need to fix this for each type. No regressions on x86-64 or x86. --- 2013-04-11 Carlos O'Donell * math/libm-test.inc (cos_test): Fix PI/2 test. (sincos_test): Likewise. * sysdeps/x86_64/fpu/libm-test-ulps: Regenerate. * sysdeps/i386/fpu/libm-test-ulps: Regenerate. --- sysdeps/i386/fpu/libm-test-ulps | 14 -------------- 1 file changed, 14 deletions(-) (limited to 'sysdeps/i386') diff --git a/sysdeps/i386/fpu/libm-test-ulps b/sysdeps/i386/fpu/libm-test-ulps index 4de455c..fecaa94 100644 --- a/sysdeps/i386/fpu/libm-test-ulps +++ b/sysdeps/i386/fpu/libm-test-ulps @@ -4149,13 +4149,6 @@ idouble: 2 ifloat: 1 ildouble: 1 ldouble: 1 -Test "cos (pi/2) == 0": -double: 1 -float: 1 -idouble: 1 -ifloat: 1 -ildouble: 1 -ldouble: 1 # cos_downward Test "cos_downward (1) == 0.5403023058681397174009366074429766037323": @@ -5513,13 +5506,6 @@ idouble: 1 ifloat: 1 ildouble: 1 ldouble: 1 -Test "sincos (pi/2, &sin_res, &cos_res) puts 0 in cos_res": -double: 1 -float: 1 -idouble: 1 -ifloat: 1 -ildouble: 1 -ldouble: 1 # sinh Test "sinh (0.75) == 0.822316731935829980703661634446913849": -- cgit v1.1