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glibc  2.9
Functions
e_gamma_r.c File Reference
#include <math.h>
#include <math_private.h>

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Functions

double __ieee754_gamma_r (double x, int *signgamp)

Function Documentation

double __ieee754_gamma_r ( double  x,
int signgamp 
)

Definition at line 26 of file e_gamma_r.c.

{
  /* We don't have a real gamma implementation now.  We'll use lgamma
     and the exp function.  But due to the required boundary
     conditions we must check some values separately.  */
  int32_t hx;
  u_int32_t lx;

  EXTRACT_WORDS (hx, lx, x);

  if (((hx & 0x7fffffff) | lx) == 0)
    {
      /* Return value for x == 0 is Inf with divide by zero exception.  */
      *signgamp = 0;
      return 1.0 / x;
    }
  if (hx < 0 && (u_int32_t) hx < 0xfff00000 && __rint (x) == x)
    {
      /* Return value for integer x < 0 is NaN with invalid exception.  */
      *signgamp = 0;
      return (x - x) / (x - x);
    }
  if ((unsigned int) hx == 0xfff00000 && lx==0)
    {
      /* x == -Inf.  According to ISO this is NaN.  */
      *signgamp = 0;
      return x - x;
    }

  /* XXX FIXME.  */
  return __ieee754_exp (__ieee754_lgamma_r (x, signgamp));
}

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