toolchain/gcc/newlib/libm/math/w_lgamma.c

   1
   2 /* @(#)w_lgamma.c 5.1 93/09/24 */
   3 /*
   4  * ====================================================
   5  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   6  *
   7  * Developed at SunPro, 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 #include <reent.h>
  23 #include <errno.h>
  24
  25 #ifndef _DOUBLE_IS_32BITS
  26
  27 #ifdef __STDC__
  28         double lgamma(double x)
  29 #else
  30         double lgamma(x)
  31         double x;
  32 #endif
  33 {
  34 #ifdef _IEEE_LIBM
  35         return __ieee754_lgamma_r(x,&(_REENT_SIGNGAM(_REENT)));
  36 #else
  37         double y;
  38         struct exception exc;
  39         y = __ieee754_lgamma_r(x,&(_REENT_SIGNGAM(_REENT)));
  40         if(_LIB_VERSION == _IEEE_) return y;
  41         if(!finite(y)&&finite(x)) {
  42 #ifndef HUGE_VAL
  43 #define HUGE_VAL inf
  44             double inf = 0.0;
  45
  46             SET_HIGH_WORD(inf,0x7ff00000);      /* set inf to infinite */
  47 #endif
  48             exc.name = "lgamma";
  49             exc.err = 0;
  50             exc.arg1 = x;
  51             exc.arg2 = x;
  52             if (_LIB_VERSION == _SVID_)
  53                exc.retval = HUGE;
  54             else
  55                exc.retval = HUGE_VAL;
  56             if(floor(x)==x&&x<=0.0) {
  57                 /* lgamma(-integer) */
  58                 exc.type = SING;
  59                 if (_LIB_VERSION == _POSIX_)
  60                    errno = EDOM;
  61                 else if (!matherr(&exc)) {
  62                    errno = EDOM;
  63                 }
  64
  65             } else {
  66                 /* lgamma(finite) overflow */
  67                 exc.type = OVERFLOW;
  68                 if (_LIB_VERSION == _POSIX_)
  69                    errno = ERANGE;
  70                 else if (!matherr(&exc)) {
  71                    errno = ERANGE;
  72                 }
  73             }
  74             if (exc.err != 0)
  75                errno = exc.err;
  76             return exc.retval;
  77         } else
  78             return y;
  79 #endif
  80 }
  81
  82 #endif /* defined(_DOUBLE_IS_32BITS) */
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