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/* @(#)w_atanh.c 5.1 93/09/24 */

/*

 * ====================================================

 * 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.

 * ====================================================

 */

/*

FUNCTION

        <<atanh>>, <<atanhf>>---inverse hyperbolic tangent

INDEX

        atanh

INDEX

        atanhf

ANSI_SYNOPSIS

        #include <math.h>

        double atanh(double <[x]>);

        float atanhf(float <[x]>);

TRAD_SYNOPSIS

        #include <math.h>

        double atanh(<[x]>)

        double <[x]>;

        float atanhf(<[x]>)

        float <[x]>;

DESCRIPTION

        <<atanh>> calculates the inverse hyperbolic tangent of <[x]>.

        <<atanhf>> is identical, other than taking and returning

        <<float>> values.

RETURNS

        <<atanh>> and <<atanhf>> return the calculated value.

        If

        @ifinfo

        |<[x]>|

        @end ifinfo

        @tex

        $|x|$

        @end tex

        is greater than 1, the global <<errno>> is set to <<EDOM>> and

        the result is a NaN.  A <<DOMAIN error>> is reported.

        If

        @ifinfo

        |<[x]>|

        @end ifinfo

        @tex

        $|x|$

        @end tex

        is 1, the global <<errno>> is set to <<EDOM>>; and the result is

        infinity with the same sign as <<x>>.  A <<SING error>> is reported.

        You can modify the error handling for these routines using

        <<matherr>>.

PORTABILITY

        Neither <<atanh>> nor <<atanhf>> are ANSI C.

QUICKREF

        atanh - pure

        atanhf - pure

*/

/*

 * wrapper atanh(x)

 */

#include "fdlibm.h"

#include <errno.h>

#ifndef _DOUBLE_IS_32BITS

#ifdef __STDC__

        double atanh(double x)          /* wrapper atanh */

#else

        double atanh(x)                 /* wrapper atanh */

        double x;

#endif

{

#ifdef _IEEE_LIBM

        return __ieee754_atanh(x);

#else

        double z,y;

        struct exception exc;

        z = __ieee754_atanh(x);

        if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;

        y = fabs(x);

        if(y>=1.0) {

            if(y>1.0) {

                /* atanh(|x|>1) */

                exc.type = DOMAIN;

                exc.name = "atanh";

                exc.err = 0;

                exc.arg1 = exc.arg2 = x;

                exc.retval = 0.0/0.0;

                if (_LIB_VERSION == _POSIX_)

                  errno = EDOM;

                else if (!matherr(&exc)) {

                  errno = EDOM;

                }

            } else {

                /* atanh(|x|=1) */

                exc.type = SING;

                exc.name = "atanh";

                exc.err = 0;

                exc.arg1 = exc.arg2 = x;

                exc.retval = x/0.0;     /* sign(x)*inf */

                if (_LIB_VERSION == _POSIX_)

                  errno = EDOM;

                else if (!matherr(&exc)) {

                  errno = EDOM;

                }

            }

            if (exc.err != 0)

              errno = exc.err;

            return exc.retval;

        } else

            return z;

#endif

}

#endif /* defined(_DOUBLE_IS_32BITS) */