110 lines
1.9 KiB
C
110 lines
1.9 KiB
C
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/* @(#)w_atanh.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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<<atanh>>, <<atanhf>>---inverse hyperbolic tangent
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INDEX
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atanh
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INDEX
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atanhf
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SYNOPSIS
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#include <math.h>
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double atanh(double <[x]>);
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float atanhf(float <[x]>);
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DESCRIPTION
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<<atanh>> calculates the inverse hyperbolic tangent of <[x]>.
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<<atanhf>> is identical, other than taking and returning
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<<float>> values.
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RETURNS
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<<atanh>> and <<atanhf>> return the calculated value.
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If
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@ifnottex
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|<[x]>|
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@end ifnottex
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@tex
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$|x|$
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@end tex
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is greater than 1, the global <<errno>> is set to <<EDOM>> and
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the result is a NaN. A <<DOMAIN error>> is reported.
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If
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@ifnottex
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|<[x]>|
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@end ifnottex
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@tex
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$|x|$
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@end tex
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is 1, the global <<errno>> is set to <<EDOM>>; and the result is
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infinity with the same sign as <<x>>. A <<SING error>> is reported.
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PORTABILITY
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Neither <<atanh>> nor <<atanhf>> are ANSI C.
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QUICKREF
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atanh - pure
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atanhf - pure
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*/
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/*
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* wrapper atanh(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 atanh(double x) /* wrapper atanh */
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#else
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double atanh(x) /* wrapper atanh */
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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_atanh(x);
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#else
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double z,y;
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z = __ieee754_atanh(x);
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if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;
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y = fabs(x);
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if(y>=1.0) {
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if(y>1.0) {
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/* atanh(|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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/* atanh(|x|=1) */
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errno = EDOM;
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return x/0.0; /* sign(x)*inf */
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}
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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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