glibc/math/w_lgamma.c

50 lines
1.3 KiB
C

/* @(#)w_lgamma.c 5.1 93/09/24 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/* double lgamma(double x)
* Return the logarithm of the Gamma function of x.
*
* Method: call __ieee754_lgamma_r
*/
#include <math.h>
#include <math_private.h>
double
__lgamma(double x)
{
int local_signgam = 0;
double y = __ieee754_lgamma_r(x,
_LIB_VERSION != _ISOC_
/* ISO C99 does not define the
global variable. */
? &signgam
: &local_signgam);
if(__builtin_expect(!isfinite(y), 0)
&& isfinite(x) && _LIB_VERSION != _IEEE_)
return __kernel_standard(x, x,
__floor(x)==x&&x<=0.0
? 15 /* lgamma pole */
: 14); /* lgamma overflow */
return y;
}
weak_alias (__lgamma, lgamma)
strong_alias (__lgamma, __gamma)
weak_alias (__gamma, gamma)
#ifdef NO_LONG_DOUBLE
strong_alias (__lgamma, __lgammal)
weak_alias (__lgamma, lgammal)
strong_alias (__gamma, __gammal)
weak_alias (__gamma, gammal)
#endif