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/* @(#)z_cosh.c 1.0 98/08/13 */

/*

FUNCTION

        <<cosh>>, <<coshf>>---hyperbolic cosine

ANSI_SYNOPSIS

        #include <math.h>

        double cosh(double <[x]>);

        float coshf(float <[x]>)

TRAD_SYNOPSIS

        #include <math.h>

        double cosh(<[x]>)

        double <[x]>;

        float coshf(<[x]>)

        float <[x]>;

DESCRIPTION

        <<cosh>> computes the hyperbolic cosine of the argument <[x]>.

        <<cosh(<[x]>)>> is defined as

        @ifnottex

        . (exp(x) + exp(-x))/2

        @end ifnottex

        @tex

        $${(e^x + e^{-x})} \over 2$$

        @end tex

        Angles are specified in radians.

        <<coshf>> is identical, save that it takes and returns <<float>>.

RETURNS

        The computed value is returned.  When the correct value would create

        an overflow,  <<cosh>> returns the value <<HUGE_VAL>> with the

        appropriate sign, and the global value <<errno>> is set to <<ERANGE>>.

        You can modify error handling for these functions using the

        function <<matherr>>.

PORTABILITY

        <<cosh>> is ANSI.

        <<coshf>> is an extension.

QUICKREF

        cosh ansi pure

        coshf - pure

*/

/******************************************************************

 * Hyperbolic Cosine

 *

 * Input:

 *   x - floating point value

 *

 * Output:

 *   hyperbolic cosine of x

 *

 * Description:

 *   This routine returns the hyperbolic cosine of x.

 *

 *****************************************************************/

#include "fdlibm.h"

#include "zmath.h"

#ifndef _DOUBLE_IS_32BITS

double

_DEFUN (cosh, (double),

        double x)

{

  return (sineh (x, 1));

}

#endif /* _DOUBLE_IS_32BITS */