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/* 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 atanhf(float x)

#else

        float 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;

}