math.c: tanh overflow

* math.c (tanh): check overflows, and return +-1.0.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55798 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 3 insertions, 1 deletions

diff --git a/math.c b/math.c
index a781167d5e..eefcec3c93 100644
--- a/math.c
+++ b/math.c
@@ -283,7 +283,9 @@ math_sinh(VALUE obj, VALUE x)
 double
 tanh(double x)
 {
-    return sinh(x) / cosh(x);
+    const double c = cosh(x);
+    if (!isinf(c)) return sinh(x) / c;
+    return x > 0 ? 1.0 : -1.0;
 }
 #endif