w_gamma.c 1.2 KB

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  1. /* @(#)w_gamma.c 5.1 93/09/24 */
  2. /*
  3. * ====================================================
  4. * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
  5. *
  6. * Developed at SunPro, a Sun Microsystems, Inc. business.
  7. * Permission to use, copy, modify, and distribute this
  8. * software is freely granted, provided that this notice
  9. * is preserved.
  10. * ====================================================
  11. */
  12. #if defined(LIBM_SCCS) && !defined(lint)
  13. static char rcsid[] = "$NetBSD: w_gamma.c,v 1.7 1995/11/20 22:06:43 jtc Exp $";
  14. #endif
  15. /* double gamma(double x)
  16. * Return the logarithm of the Gamma function of x.
  17. *
  18. * Method: call gamma_r
  19. */
  20. #include <math.h>
  21. #include "math_private.h"
  22. libm_hidden_proto(signgam)
  23. #ifdef __STDC__
  24. double gamma(double x)
  25. #else
  26. double gamma(x)
  27. double x;
  28. #endif
  29. {
  30. #ifdef _IEEE_LIBM
  31. return __ieee754_lgamma_r(x,&signgam);
  32. #else
  33. double y;
  34. y = __ieee754_lgamma_r(x,&signgam);
  35. if(_LIB_VERSION == _IEEE_) return y;
  36. if(!finite(y)&&finite(x)) {
  37. if(floor(x)==x&&x<=0.0)
  38. return __kernel_standard(x,x,41); /* gamma pole */
  39. else
  40. return __kernel_standard(x,x,40); /* gamma overflow */
  41. } else
  42. return y;
  43. #endif
  44. }