From 83cfc94563c3f5eb0339f4cab280e5219a179a0c Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Tue, 2 Aug 2016 12:40:51 +0000
Subject: 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
---
 math.c                 | 4 +++-
 test/ruby/test_math.rb | 2 ++
 2 files changed, 5 insertions(+), 1 deletion(-)

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
 
diff --git a/test/ruby/test_math.rb b/test/ruby/test_math.rb
index ac9ab3c961..f226287442 100644
--- a/test/ruby/test_math.rb
+++ b/test/ruby/test_math.rb
@@ -111,6 +111,8 @@ class TestMath < Test::Unit::TestCase
     check(Math.sinh(0) / Math.cosh(0), Math.tanh(0))
     check(Math.sinh(1) / Math.cosh(1), Math.tanh(1))
     check(Math.sinh(2) / Math.cosh(2), Math.tanh(2))
+    check(+1.0, Math.tanh(+1000.0))
+    check(-1.0, Math.tanh(-1000.0))
   end
 
   def test_acosh
-- 
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