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w_lgamma.c
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1 
2 /* @(#)w_lgamma.c 1.3 95/01/18 */
3 /*
4  * ====================================================
5  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6  *
7  * Developed at SunSoft, a Sun Microsystems, Inc. business.
8  * Permission to use, copy, modify, and distribute this
9  * software is freely granted, provided that this notice
10  * is preserved.
11  * ====================================================
12  *
13  */
14 
15 /* double lgamma(double x)
16  * Return the logarithm of the Gamma function of x.
17  *
18  * Method: call __ieee754_lgamma_r
19  */
20 
21 #include "fdlibm.h"
22 
23 extern int signgam;
24 
25 #ifdef __STDC__
26  double lgamma(double x)
27 #else
28  double lgamma(x)
29  double x;
30 #endif
31 {
32 #ifdef _IEEE_LIBM
33  return __ieee754_lgamma_r(x,&signgam);
34 #else
35  double y;
37  if(_LIB_VERSION == _IEEE_) return y;
38  if(!finite(y)&&finite(x)) {
39  if(floor(x)==x&&x<=0.0)
40  return __kernel_standard(x,x,15); /* lgamma pole */
41  else
42  return __kernel_standard(x,x,14); /* lgamma overflow */
43  } else
44  return y;
45 #endif
46 }