newlib/libm/math/wr_gamma.c

   1
   2 /* @(#)wr_gamma.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  * wrapper double gamma_r(double x, int *signgamp)
  16  */
  17
  18 #include "fdlibm.h"
  19 #include <errno.h>
  20
  21 #ifndef _DOUBLE_IS_32BITS
  22
  23 #ifdef __STDC__
  24         double gamma_r(double x, int *signgamp) /* wrapper lgamma_r */
  25 #else
  26         double gamma_r(x,signgamp)              /* wrapper lgamma_r */
  27         double x; int *signgamp;
  28 #endif
  29 {
  30 #ifdef _IEEE_LIBM
  31         return __ieee754_gamma_r(x,signgamp);
  32 #else
  33         double y;
  34         struct exception exc;
  35         y = __ieee754_gamma_r(x,signgamp);
  36         if(_LIB_VERSION == _IEEE_) return y;
  37         if(!finite(y)&&finite(x)) {
  38 #ifndef HUGE_VAL
  39 #define HUGE_VAL inf
  40             double inf = 0.0;
  41
  42             SET_HIGH_WORD(inf,0x7ff00000);      /* set inf to infinite */
  43 #endif
  44             exc.name = "gamma";
  45             exc.err = 0;
  46             exc.arg1 = exc.arg2 = (double)x;
  47             if (_LIB_VERSION == _SVID_)
  48                 exc.retval = HUGE;
  49             else
  50                 exc.retval = HUGE_VAL;
  51             if(floor(x)==x&&x<=0.0) {
  52                 /* gamma(-integer) or gamma(0) */
  53                 exc.type = SING;
  54                 if (_LIB_VERSION == _POSIX_)
  55                   errno = EDOM;
  56                 else if (!matherr(&exc)) {
  57                   errno = EDOM;
  58                 }
  59             } else {
  60                 /* gamma(finite) overflow */
  61                 exc.type = OVERFLOW;
  62                 if (_LIB_VERSION == _POSIX_)
  63                   errno = ERANGE;
  64                 else if (!matherr(&exc)) {
  65                   errno = ERANGE;
  66                 }
  67             }
  68             if (exc.err != 0)
  69                errno = exc.err;
  70             return exc.retval;
  71         } else
  72             return y;
  73 #endif
  74 }
  75
  76 #endif /* defined(_DOUBLE_IS_32BITS) */