Bug #10642: 2.2: TestMath#test_gamma test failure (MinGW)

• Status: Third Party's Issue
• Assignee: naruse (Yui NARUSE)
• Target version: -
• ruby -v: ruby 2.2.0dev (2014-12-24) [i386-mingw32]
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN

[luislavena (Luis Lavena)]

Hello,

Running tests against ruby_2_2 branch, mingw-w64 4.7.2, Windows 7 x64:

TestMath#test_gamma [C:/Users/Luis/Code/ruby/ruby/test/ruby/test_math.rb:237]:
Math.gamma(2147483648) should be INF.
Expected NaN to be infinite?.

[wanabe (_ wanabe)]

http://sourceforge.net/p/mingw-w64/mingw-w64/ci/8a67ab4541226a80b3ec2047347890d915126de1/tree/mingw-w64-crt/math/tgamma.c#l122
tgamma() of mingw32-w64 is buggy in x > 709.782712893384 because pow(x, 0.5 * x - 0.25) / exp(x) == Inf / Inf == NaN.
It doesn't care of x > 172.

I guess the ticket should be "3rd party's issue", shouldn't it?
If you're going to insist, how about using missing/tgamma.c on mingw32-w64?

[naruse (Yui NARUSE)]

• Status changed from Assigned to Third Party's Issue

[moritat (Tsuyoshi Morita)]

This issue keep failing in ruby_2_2 branch.
Please backport r49913.

[usa (Usaku NAKAMURA)]

• Related to Bug #12249: Math.gamma(-0.0) should return -Infinity added