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glibc  2.9
Functions
e_remainder.c File Reference
#include "endian.h"
#include "mydefs.h"
#include "urem.h"
#include "MathLib.h"
#include "math_private.h"

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Functions

double __ieee754_remainder (double x, double y)

Function Documentation

double __ieee754_remainder ( double  x,
double  y 
)

Definition at line 43 of file e_remainder.c.

{
  double z,d,xx;
#if 0
  double yy;
#endif
  int4 kx,ky,n,nn,n1,m1,l;
#if 0
  int4 m;
#endif
  mynumber u,t,w={{0,0}},v={{0,0}},ww={{0,0}},r;
  u.x=x;
  t.x=y;
  kx=u.i[HIGH_HALF]&0x7fffffff; /* no sign  for x*/
  t.i[HIGH_HALF]&=0x7fffffff;   /*no sign for y */
  ky=t.i[HIGH_HALF];
  /*------ |x| < 2^1023  and   2^-970 < |y| < 2^1024 ------------------*/
  if (kx<0x7fe00000 && ky<0x7ff00000 && ky>=0x03500000) {
    if (kx+0x00100000<ky) return x;
    if ((kx-0x01500000)<ky) {
      z=x/t.x;
      v.i[HIGH_HALF]=t.i[HIGH_HALF];
      d=(z+big.x)-big.x;
      xx=(x-d*v.x)-d*(t.x-v.x);
      if (d-z!=0.5&&d-z!=-0.5) return (xx!=0)?xx:((x>0)?ZERO.x:nZERO.x);
      else {
       if (ABS(xx)>0.5*t.x) return (z>d)?xx-t.x:xx+t.x;
       else return xx;
      }
    }   /*    (kx<(ky+0x01500000))         */
    else  {
      r.x=1.0/t.x;
      n=t.i[HIGH_HALF];
      nn=(n&0x7ff00000)+0x01400000;
      w.i[HIGH_HALF]=n;
      ww.x=t.x-w.x;
      l=(kx-nn)&0xfff00000;
      n1=ww.i[HIGH_HALF];
      m1=r.i[HIGH_HALF];
      while (l>0) {
       r.i[HIGH_HALF]=m1-l;
       z=u.x*r.x;
       w.i[HIGH_HALF]=n+l;
       ww.i[HIGH_HALF]=(n1)?n1+l:n1;
       d=(z+big.x)-big.x;
       u.x=(u.x-d*w.x)-d*ww.x;
       l=(u.i[HIGH_HALF]&0x7ff00000)-nn;
      }
      r.i[HIGH_HALF]=m1;
      w.i[HIGH_HALF]=n;
      ww.i[HIGH_HALF]=n1;
      z=u.x*r.x;
      d=(z+big.x)-big.x;
      u.x=(u.x-d*w.x)-d*ww.x;
      if (ABS(u.x)<0.5*t.x) return (u.x!=0)?u.x:((x>0)?ZERO.x:nZERO.x);
      else
        if (ABS(u.x)>0.5*t.x) return (d>z)?u.x+t.x:u.x-t.x;
        else
        {z=u.x/t.x; d=(z+big.x)-big.x; return ((u.x-d*w.x)-d*ww.x);}
    }

  }   /*   (kx<0x7fe00000&&ky<0x7ff00000&&ky>=0x03500000)     */
  else {
    if (kx<0x7fe00000&&ky<0x7ff00000&&(ky>0||t.i[LOW_HALF]!=0)) {
      y=ABS(y)*t128.x;
      z=__ieee754_remainder(x,y)*t128.x;
      z=__ieee754_remainder(z,y)*tm128.x;
      return z;
    }
  else {
    if ((kx&0x7ff00000)==0x7fe00000&&ky<0x7ff00000&&(ky>0||t.i[LOW_HALF]!=0)) {
      y=ABS(y);
      z=2.0*__ieee754_remainder(0.5*x,y);
      d = ABS(z);
      if (d <= ABS(d-y)) return z;
      else return (z>0)?z-y:z+y;
    }
    else { /* if x is too big */
      if (kx == 0x7ff00000 && u.i[LOW_HALF] == 0 && y == 1.0)
       return x / x;
      if (kx>=0x7ff00000||(ky==0&&t.i[LOW_HALF]==0)||ky>0x7ff00000||
         (ky==0x7ff00000&&t.i[LOW_HALF]!=0))
       return (u.i[HIGH_HALF]&0x80000000)?nNAN.x:NAN.x;
      else return x;
    }
   }
  }
}

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