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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
This commit is contained in:
nobu 2016-08-02 12:40:51 +00:00
parent aa8e9c63ad
commit 83cfc94563
2 changed files with 5 additions and 1 deletions

4
math.c
View file

@ -283,7 +283,9 @@ math_sinh(VALUE obj, VALUE x)
double double
tanh(double x) 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 #endif

View file

@ -111,6 +111,8 @@ class TestMath < Test::Unit::TestCase
check(Math.sinh(0) / Math.cosh(0), Math.tanh(0)) check(Math.sinh(0) / Math.cosh(0), Math.tanh(0))
check(Math.sinh(1) / Math.cosh(1), Math.tanh(1)) check(Math.sinh(1) / Math.cosh(1), Math.tanh(1))
check(Math.sinh(2) / Math.cosh(2), Math.tanh(2)) 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 end
def test_acosh def test_acosh