nobu	2016-08-02 21:40:51 +0900 (Tue, 02 Aug 2016)

  New Revision: 55798

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=55798

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

  Modified files:
    trunk/math.c
    trunk/test/ruby/test_math.rb
Index: math.c
===================================================================
--- math.c	(revision 55797)
+++ math.c	(revision 55798)
@@ -283,7 +283,9 @@ math_sinh(VALUE obj, VALUE x) https://github.com/ruby/ruby/blob/trunk/math.c#L283
 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
 
Index: test/ruby/test_math.rb
===================================================================
--- test/ruby/test_math.rb	(revision 55797)
+++ test/ruby/test_math.rb	(revision 55798)
@@ -111,6 +111,8 @@ class TestMath < Test::Unit::TestCase https://github.com/ruby/ruby/blob/trunk/test/ruby/test_math.rb#L111
     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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