glibc/math/w_pow.c

79 lines
2.0 KiB
C

/* Copyright (C) 2011-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <math.h>
#include <math_private.h>
/* wrapper pow */
double
__pow (double x, double y)
{
double z = __ieee754_pow (x, y);
if (__glibc_unlikely (!isfinite (z)))
{
if (_LIB_VERSION != _IEEE_)
{
if (isnan (x))
{
if (y == 0.0)
/* pow(NaN,0.0) */
return __kernel_standard (x, y, 42);
}
else if (isfinite (x) && isfinite (y))
{
if (isnan (z))
/* pow neg**non-int */
return __kernel_standard (x, y, 24);
else if (x == 0.0 && y < 0.0)
{
if (signbit (x) && signbit (z))
/* pow(-0.0,negative) */
return __kernel_standard (x, y, 23);
else
/* pow(+0.0,negative) */
return __kernel_standard (x, y, 43);
}
else
/* pow overflow */
return __kernel_standard (x, y, 21);
}
}
}
else if (__builtin_expect (z == 0.0, 0) && isfinite (x) && isfinite (y)
&& _LIB_VERSION != _IEEE_)
{
if (x == 0.0)
{
if (y == 0.0)
/* pow(0.0,0.0) */
return __kernel_standard (x, y, 20);
}
else
/* pow underflow */
return __kernel_standard (x, y, 22);
}
return z;
}
weak_alias (__pow, pow)
#ifdef NO_LONG_DOUBLE
strong_alias (__pow, __powl)
weak_alias (__pow, powl)
#endif