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glibc  2.9
Functions
multc3.c File Reference
#include <stdbool.h>
#include <math.h>
#include <complex.h>

Go to the source code of this file.

Functions

attribute_hidden long double
_Complex 
__multc3 (long double a, long double b, long double c, long double d)

Function Documentation

attribute_hidden long double _Complex __multc3 ( long double  a,
long double  b,
long double  c,
long double  d 
)

Definition at line 26 of file multc3.c.

{
  long double ac, bd, ad, bc, x, y;

  ac = a * c;
  bd = b * d;
  ad = a * d;
  bc = b * c;

  x = ac - bd;
  y = ad + bc;

  if (isnan (x) && isnan (y))
    {
      /* Recover infinities that computed as NaN + iNaN.  */
      bool recalc = 0;
      if (isinf (a) || isinf (b))
       {
         /* z is infinite.  "Box" the infinity and change NaNs in
            the other factor to 0.  */
         a = __copysignl (isinf (a) ? 1 : 0, a);
         b = __copysignl (isinf (b) ? 1 : 0, b);
         if (isnan (c)) c = __copysignl (0, c);
         if (isnan (d)) d = __copysignl (0, d);
         recalc = 1;
       }
     if (isinf (c) || isinf (d))
       {
         /* w is infinite.  "Box" the infinity and change NaNs in
            the other factor to 0.  */
         c = __copysignl (isinf (c) ? 1 : 0, c);
         d = __copysignl (isinf (d) ? 1 : 0, d);
         if (isnan (a)) a = __copysignl (0, a);
         if (isnan (b)) b = __copysignl (0, b);
         recalc = 1;
       }
     if (!recalc
         && (isinf (ac) || isinf (bd) || isinf (ad) || isinf (bc)))
       {
         /* Recover infinities from overflow by changing NaNs to 0.  */
         if (isnan (a)) a = __copysignl (0, a);
         if (isnan (b)) b = __copysignl (0, b);
         if (isnan (c)) c = __copysignl (0, c);
         if (isnan (d)) d = __copysignl (0, d);
         recalc = 1;
       }
      if (recalc)
       {
         x = INFINITY * (a * c - b * d);
         y = INFINITY * (a * d + b * c);
       }
    }

  return x + I * y;
}

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