101 lines
1.9 KiB
C
101 lines
1.9 KiB
C
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/* @(#)w_acosh.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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/*
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FUNCTION
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<<acosh>>, <<acoshf>>---inverse hyperbolic cosine
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INDEX
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acosh
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INDEX
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acoshf
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SYNOPSIS
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#include <math.h>
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double acosh(double <[x]>);
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float acoshf(float <[x]>);
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DESCRIPTION
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<<acosh>> calculates the inverse hyperbolic cosine of <[x]>.
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<<acosh>> is defined as
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@ifnottex
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. log(<[x]> + sqrt(<[x]>*<[x]>-1))
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@end ifnottex
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@tex
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$$ln\Bigl(x + \sqrt{x^2-1}\Bigr)$$
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@end tex
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<[x]> must be a number greater than or equal to 1.
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<<acoshf>> is identical, other than taking and returning floats.
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RETURNS
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<<acosh>> and <<acoshf>> return the calculated value. If <[x]>
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less than 1, the return value is NaN and <<errno>> is set to <<EDOM>>.
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PORTABILITY
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Neither <<acosh>> nor <<acoshf>> are ANSI C. They are not recommended
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for portable programs.
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QUICKREF
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ansi posix rentrant
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acos n,n,m
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acosf n,n,m
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MATHREF
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acosh, NAN, arg,DOMAIN,EDOM
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acosh, < 1.0, NAN,DOMAIN,EDOM
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acosh, >=1.0, acosh(arg),,,
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MATHREF
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acoshf, NAN, arg,DOMAIN,EDOM
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acoshf, < 1.0, NAN,DOMAIN,EDOM
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acoshf, >=1.0, acosh(arg),,,
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*/
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/*
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* wrapper acosh(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 acosh(double x) /* wrapper acosh */
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#else
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double acosh(x) /* wrapper acosh */
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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_acosh(x);
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#else
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double z;
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z = __ieee754_acosh(x);
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if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;
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if(x<1.0) {
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/* acosh(x<1) */
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errno = EDOM;
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return 0.0/0.0;
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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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