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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
@ifinfo
. (exp(x) + exp(-x))/2
@end ifinfo
@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 */
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