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117 lines
2.4 KiB
C
117 lines
2.4 KiB
C
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/* @(#)w_cosh.c 5.1 93/09/24 */
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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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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@ifnottex
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. (exp(x) + exp(-x))/2
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@end ifnottex
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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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* wrapper cosh(x)
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*/
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#include "fdlibm.h"
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#include <errno.h>
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#ifndef _DOUBLE_IS_32BITS
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#ifdef __STDC__
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double cosh(double x) /* wrapper cosh */
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#else
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double cosh(x) /* wrapper cosh */
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double x;
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#endif
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{
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#ifdef _IEEE_LIBM
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return __ieee754_cosh(x);
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#else
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double z;
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struct exception exc;
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z = __ieee754_cosh(x);
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if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;
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if(fabs(x)>7.10475860073943863426e+02) {
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/* cosh(finite) overflow */
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#ifndef HUGE_VAL
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#define HUGE_VAL inf
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double inf = 0.0;
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SET_HIGH_WORD(inf,0x7ff00000); /* set inf to infinite */
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#endif
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exc.type = OVERFLOW;
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exc.name = "cosh";
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exc.err = 0;
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exc.arg1 = exc.arg2 = x;
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if (_LIB_VERSION == _SVID_)
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exc.retval = HUGE;
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else
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exc.retval = HUGE_VAL;
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if (_LIB_VERSION == _POSIX_)
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errno = ERANGE;
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else if (!matherr(&exc)) {
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errno = ERANGE;
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}
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if (exc.err != 0)
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errno = exc.err;
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return exc.retval;
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} else
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return z;
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#endif
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}
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#endif /* defined(_DOUBLE_IS_32BITS) */
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