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Fix Math.cbrt(0.0) on glibc

This should return 0, but on glibc it returned NaN.

Fixes [Bug #17804]
This commit is contained in:
Jeremy Evans 2021-04-28 13:35:22 -07:00
parent b7fec2e3e5
commit 406ae7fb03
Notes: git 2021-05-09 06:45:55 +09:00
2 changed files with 2 additions and 1 deletions

2
math.c
View file

@ -703,7 +703,7 @@ math_cbrt(VALUE unused_obj, VALUE x)
double f = Get_Double(x);
double r = cbrt(f);
#if defined __GLIBC__
if (isfinite(r)) {
if (isfinite(r) && !(f == 0.0 && r == 0.0)) {
r = (2.0 * r + (f / r / r)) / 3.0;
}
#endif

View file

@ -201,6 +201,7 @@ class TestMath < Test::Unit::TestCase
check(-2, Math.cbrt(-8))
check(3, Math.cbrt(27))
check(-0.1, Math.cbrt(-0.001))
check(0.0, Math.cbrt(0.0))
assert_nothing_raised { assert_infinity(Math.cbrt(1.0/0)) }
assert_operator(Math.cbrt(1.0 - Float::EPSILON), :<=, 1.0)
end