Quelle s_atanf.cpp Sprache: C

/* s_atanf.c -- float version of s_atan.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.
* ====================================================
*/

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

#include "math_private.h"

static const float atanhi[] = {
  4.6364760399e-01, /* atan(0.5)hi 0x3eed6338 */
  7.8539812565e-01, /* atan(1.0)hi 0x3f490fda */
  9.8279368877e-01, /* atan(1.5)hi 0x3f7b985e */
  1.5707962513e+00, /* atan(inf)hi 0x3fc90fda */
};

static const float atanlo[] = {
  5.0121582440e-09, /* atan(0.5)lo 0x31ac3769 */
  3.7748947079e-08, /* atan(1.0)lo 0x33222168 */
  3.4473217170e-08, /* atan(1.5)lo 0x33140fb4 */
  7.5497894159e-08, /* atan(inf)lo 0x33a22168 */
};

static const float aT[] = {
  3.3333328366e-01,
-1.9999158382e-01,
  1.4253635705e-01,
-1.0648017377e-01,
  6.1687607318e-02,
};

static const float
one   = 1.0,
huge   = 1.0e30;

float
atanf(float x)
{
float w,s1,s2,z;
int32_t ix,hx,id;

GET_FLOAT_WORD(hx,x);
ix = hx&0x7fffffff;
if(ix>=0x4c800000) { /* if |x| >= 2**26 */
     if(ix>0x7f800000)
  return x+x;  /* NaN */
     if(hx>0) return  atanhi[3]+*(volatile float *)&atanlo[3];
     else     return -atanhi[3]-*(volatile float *)&atanlo[3];
} if (ix < 0x3ee00000) { /* |x| < 0.4375 */
     if (ix < 0x39800000) { /* |x| < 2**-12 */
  if(huge+x>one) return x; /* raise inexact */
     }
     id = -1;
} else {
x = fabsf(x);
if (ix < 0x3f980000) {  /* |x| < 1.1875 */
     if (ix < 0x3f300000) { /* 7/16 <=|x|<11/16 */
  id = 0; x = ((float)2.0*x-one)/((float)2.0+x);
     } else {   /* 11/16<=|x|< 19/16 */
  id = 1; x  = (x-one)/(x+one);
     }
} else {
     if (ix < 0x401c0000) { /* |x| < 2.4375 */
  id = 2; x  = (x-(float)1.5)/(one+(float)1.5*x);
     } else {   /* 2.4375 <= |x| < 2**26 */
  id = 3; x  = -(float)1.0/x;
     }
}}
    /* end of argument reduction */
z = x*x;
w = z*z;
    /* break sum from i=0 to 10 aT[i]z**(i+1) into odd and even poly */
s1 = z*(aT[0]+w*(aT[2]+w*aT[4]));
s2 = w*(aT[1]+w*aT[3]);
if (id<0) return x - x*(s1+s2);
else {
     z = atanhi[id] - ((x*(s1+s2) - atanlo[id]) - x);
     return (hx<0)? -z:z;
}
}

quality100%

¤ Dauer der Verarbeitung: 0.13 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.