Quelle e_sqrtf.cpp Sprache: C

/* e_sqrtf.c -- float version of e_sqrt.c.
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
*/

/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/

//#ifndef lint
//static char rcsid[] = "$FreeBSD$";
//#endif

#include "math_private.h"

#ifdef USE_BUILTIN_SQRTF
float
__ieee754_sqrtf(float x)
{
return (__builtin_sqrtf(x));
}
#else
static const float one = 1.0, tiny=1.0e-30;

float
__ieee754_sqrtf(float x)
{
float z;
int32_t sign = (int)0x80000000;
int32_t ix,s,q,m,t,i;
u_int32_t r;

GET_FLOAT_WORD(ix,x);

    /* take care of Inf and NaN */
if((ix&0x7f800000)==0x7f800000) {
     return x*x+x;  /* sqrt(NaN)=NaN, sqrt(+inf)=+inf
   sqrt(-inf)=sNaN */
}
    /* take care of zero */
if(ix<=0) {
     if((ix&(~sign))==0) return x;/* sqrt(+-0) = +-0 */
     else if(ix<0)
  return (x-x)/(x-x);  /* sqrt(-ve) = sNaN */
}
    /* normalize x */
m = (ix>>23);
if(m==0) {    /* subnormal x */
     for(i=0;(ix&0x00800000)==0;i++) ix<<=1;
     m -= i-1;
}
m -= 127; /* unbias exponent */
ix = (ix&0x007fffff)|0x00800000;
if(m&1) /* odd m, double x to make it even */
     ix += ix;
m >>= 1; /* m = [m/2] */

    /* generate sqrt(x) bit by bit */
ix += ix;
q = s = 0;  /* q = sqrt(x) */
r = 0x01000000;  /* r = moving bit from right to left */

while(r!=0) {
     t = s+r;
     if(t<=ix) {
  s    = t+r;
  ix  -= t;
  q   += r;
     }
     ix += ix;
     r>>=1;
}

    /* use floating add to find out rounding direction */
if(ix!=0) {
     z = one-tiny; /* trigger inexact flag */
     if (z>=one) {
         z = one+tiny;
  if (z>one)
      q += 2;
  else
      q += (q&1);
     }
}
ix = (q>>1)+0x3f000000;
ix += (m <<23);
SET_FLOAT_WORD(z,ix);
return z;
}
#endif

quality86%

¤ Dauer der Verarbeitung: 0.1 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.