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/* @(#)w_acos.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

        <<acos>>, <<acosf>>---arc cosine

INDEX

        acos

INDEX

        acosf

ANSI_SYNOPSIS

        #include <math.h>

        double acos(double <[x]>);

        float acosf(float <[x]>);

TRAD_SYNOPSIS

        #include <math.h>

        double acos(<[x]>)

        double <[x]>;

        float acosf(<[x]>)

        float <[x]>;

DESCRIPTION

        <<acos>> computes the inverse cosine (arc cosine) of the input value.

        Arguments to <<acos>> must be in the range @minus{}1 to 1.

        <<acosf>> is identical to <<acos>>, except that it performs

        its calculations on <<floats>>.

RETURNS

        @ifinfo

        <<acos>> and <<acosf>> return values in radians, in the range of 0 to pi.

        @end ifinfo

        @tex

        <<acos>> and <<acosf>> return values in radians, in the range of <<0>> to $\pi$.

        @end tex

        If <[x]> is not between @minus{}1 and 1, the returned value is NaN

        (not a number) the global variable <<errno>> is set to <<EDOM>>, and a

        <<DOMAIN error>> message is sent as standard error output.

        You can modify error handling for these functions using <<matherr>>.

QUICKREF ANSI SVID POSIX RENTRANT

 acos    y,y,y,m

 acosf   n,n,n,m

MATHREF

 acos, [-1,1], acos(arg),,,

 acos, NAN,    arg,DOMAIN,EDOM

MATHREF

 acosf, [-1,1], acosf(arg),,,

 acosf, NAN,    argf,DOMAIN,EDOM

*/

/*

 * wrap_acos(x)

 */

#include "fdlibm.h"

#include <errno.h>

#ifndef _DOUBLE_IS_32BITS

#ifdef __STDC__

        double acos(double x)           /* wrapper acos */

#else

        double acos(x)                  /* wrapper acos */

        double x;

#endif

{

#ifdef _IEEE_LIBM

        return __ieee754_acos(x);

#else

        double z;

        struct exception exc;

        z = __ieee754_acos(x);

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

        if(fabs(x)>1.0) {

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

            exc.type = DOMAIN;

            exc.name = "acos";

            exc.err = 0;

            exc.arg1 = exc.arg2 = x;

            exc.retval = 0.0;

            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) */