81 lines
1.6 KiB
C
81 lines
1.6 KiB
C
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/* @(#)z_cosh.c 1.0 98/08/13 */
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/*
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FUNCTION
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<<cosh>>, <<coshf>>---hyperbolic cosine
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ANSI_SYNOPSIS
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#include <math.h>
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double cosh(double <[x]>);
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float coshf(float <[x]>)
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TRAD_SYNOPSIS
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#include <math.h>
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double cosh(<[x]>)
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double <[x]>;
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float coshf(<[x]>)
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float <[x]>;
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DESCRIPTION
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<<cosh>> computes the hyperbolic cosine of the argument <[x]>.
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<<cosh(<[x]>)>> is defined as
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@ifinfo
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. (exp(x) + exp(-x))/2
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@end ifinfo
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@tex
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$${(e^x + e^{-x})} \over 2$$
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@end tex
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Angles are specified in radians.
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<<coshf>> is identical, save that it takes and returns <<float>>.
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RETURNS
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The computed value is returned. When the correct value would create
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an overflow, <<cosh>> returns the value <<HUGE_VAL>> with the
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appropriate sign, and the global value <<errno>> is set to <<ERANGE>>.
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You can modify error handling for these functions using the
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function <<matherr>>.
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PORTABILITY
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<<cosh>> is ANSI.
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<<coshf>> is an extension.
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QUICKREF
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cosh ansi pure
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coshf - pure
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*/
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/******************************************************************
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* Hyperbolic Cosine
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*
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* Input:
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* x - floating point value
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*
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* Output:
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* hyperbolic cosine of x
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*
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* Description:
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* This routine returns the hyperbolic cosine of x.
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*
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*****************************************************************/
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#include "fdlibm.h"
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#include "zmath.h"
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#ifndef _DOUBLE_IS_32BITS
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double
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_DEFUN (cosh, (double),
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double x)
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{
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return (sineh (x, 1));
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}
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#endif /* _DOUBLE_IS_32BITS */
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