Quelle e_log10f.cpp Sprache: C

/*
* ====================================================
* 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.
* ====================================================
*/

//#include <sys/cdefs.h>
//__FBSDID("$FreeBSD$");

/*
* Float version of e_log10.c.  See the latter for most comments.
*/

#include "math.h"
#include "math_private.h"
#include "k_logf.h"

static const float
two25      =  3.3554432000e+07, /* 0x4c000000 */
ivln10hi   =  4.3432617188e-01, /* 0x3ede6000 */
ivln10lo   = -3.1689971365e-05, /* 0xb804ead9 */
log10_2hi  =  3.0102920532e-01, /* 0x3e9a2080 */
log10_2lo  =  7.9034151668e-07; /* 0x355427db */

static const float zero   =  0.0;
static volatile float vzero = 0.0;

float
__ieee754_log10f(float x)
{
float f,hfsq,hi,lo,r,y;
int32_t i,k,hx;

GET_FLOAT_WORD(hx,x);

k=0;
if (hx < 0x00800000) {   /* x < 2**-126  */
     if ((hx&0x7fffffff)==0)
  return -two25/vzero;  /* log(+-0)=-inf */
     if (hx<0) return (x-x)/zero; /* log(-#) = NaN */
     k -= 25; x *= two25; /* subnormal number, scale up x */
     GET_FLOAT_WORD(hx,x);
}
if (hx >= 0x7f800000) return x+x;
if (hx == 0x3f800000)
     return zero;   /* log(1) = +0 */
k += (hx>>23)-127;
hx &= 0x007fffff;
i = (hx+(0x4afb0d))&0x800000;
SET_FLOAT_WORD(x,hx|(i^0x3f800000)); /* normalize x or x/2 */
k += (i>>23);
y = (float)k;
f = x - (float)1.0;
hfsq = (float)0.5*f*f;
r = k_log1pf(f);

/* See e_log2f.c and e_log2.c for details. */
if (sizeof(float_t) > sizeof(float))
  return (r - hfsq + f) * ((float_t)ivln10lo + ivln10hi) +
      y * ((float_t)log10_2lo + log10_2hi);
hi = f - hfsq;
GET_FLOAT_WORD(hx,hi);
SET_FLOAT_WORD(hi,hx&0xfffff000);
lo = (f - hi) - hfsq + r;
return y*log10_2lo + (lo+hi)*ivln10lo + lo*ivln10hi + hi*ivln10hi +
     y*log10_2hi;
}

quality100%

¤ Dauer der Verarbeitung: 0.10 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.