* configure.in (rb_cv_lgamma_r_pm0): check if lgamma_r(+0.0)

  returns positive infinity, in addition to lgamma_r(-0.0).
  AIX returns an incorrect result of negative infinity.

* math.c (ruby_lgamma_r): handle +0.0, in addition to -0.0.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54803 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 4 insertions, 1 deletions

diff --git a/math.c b/math.c
index 9ac898f0ba..c3fe7dbd09 100644
--- a/math.c
+++ b/math.c
@@ -750,7 +750,7 @@ ruby_tgamma(const double d)
 #define tgamma(d) ruby_tgamma(d)
 #endif
 
-#if defined LGAMMA_R_M0_FIX
+#if defined LGAMMA_R_PM0_FIX
 static inline double
 ruby_lgamma_r(const double d, int *sign)
 {
@@ -759,6 +759,9 @@ ruby_lgamma_r(const double d, int *sign)
 	if (d == 0.0 && signbit(d)) {
 	    *sign = -1;
 	    return INFINITY;
+	} else if (d == 0.0 && !signbit(d)) {
+	    *sign = 1;
+	    return INFINITY;
 	}
     }
     return g;