lgamma: fix sign handling

add testcase from
http://sourceware.org/bugzilla/show_bug.cgi?id=4407

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/test/math/signgam.c b/test/math/signgam.c
new file mode 100644
index 000000000..c60375aec
--- /dev/null
+++ b/test/math/signgam.c
@@ -0,0 +1,18 @@
+#define _XOPEN_SOURCE 600
+#include <math.h>
+#include <stdio.h>
+
+double zero = 0.0;
+double mzero;
+
+int
+main (void)
+{
+  double d;
+  mzero = copysign (zero, -1.0);
+  d = lgamma (zero);
+  printf ("%g %d\n", d, signgam);
+  d = lgamma (mzero);
+  printf ("%g %d\n", d, signgam);
+  return 0;
+}