newlib-cygwin/newlib/libm/math/ef_atanh.c

55 lines
1.2 KiB
C

/* ef_atanh.c -- float version of e_atanh.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 "fdlibm.h"
#ifdef __STDC__
static const float one = 1.0, huge = 1e30;
#else
static float one = 1.0, huge = 1e30;
#endif
#ifdef __STDC__
static const float zero = 0.0;
#else
static float zero = 0.0;
#endif
#ifdef __STDC__
float __ieee754_atanhf(float x)
#else
float __ieee754_atanhf(x)
float x;
#endif
{
float t;
__int32_t hx,ix;
GET_FLOAT_WORD(hx,x);
ix = hx&0x7fffffff;
if (ix>0x3f800000) /* |x|>1 */
return (x-x)/(x-x);
if(ix==0x3f800000)
return x/zero;
if(ix<0x31800000&&(huge+x)>zero) return x; /* x<2**-28 */
SET_FLOAT_WORD(x,ix);
if(ix<0x3f000000) { /* x < 0.5 */
t = x+x;
t = (float)0.5*log1pf(t+t*x/(one-x));
} else
t = (float)0.5*log1pf((x+x)/(one-x));
if(hx>=0) return t; else return -t;
}