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/* origin: FreeBSD /usr/src/lib/msun/src/e_atanhf.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 "libm.h"
static const float one = 1.0, huge = 1e30;
static const float zero = 0.0;
float atanhf(float x)
{
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) /* x < 2**-28 */
return x;
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;
return -t;
}
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