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/* @(#)w_atanh.c 5.1 93/09/24 */
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
/*
FUNCTION
<<atanh>>, <<atanhf>>---inverse hyperbolic tangent
INDEX
atanh
INDEX
atanhf
SYNOPSIS
#include <math.h>
double atanh(double <[x]>);
float atanhf(float <[x]>);
DESCRIPTION
<<atanh>> calculates the inverse hyperbolic tangent of <[x]>.
<<atanhf>> is identical, other than taking and returning
<<float>> values.
RETURNS
<<atanh>> and <<atanhf>> return the calculated value.
If
@ifnottex
|<[x]>|
@end ifnottex
@tex
$|x|$
@end tex
is greater than 1, the global <<errno>> is set to <<EDOM>> and
the result is a NaN. A <<DOMAIN error>> is reported.
If
@ifnottex
|<[x]>|
@end ifnottex
@tex
$|x|$
@end tex
is 1, the global <<errno>> is set to <<EDOM>>; and the result is
infinity with the same sign as <<x>>. A <<SING error>> is reported.
PORTABILITY
Neither <<atanh>> nor <<atanhf>> are ANSI C.
QUICKREF
atanh - pure
atanhf - pure
*/
/*
* wrapper atanh(x)
*/
#include "fdlibm.h"
#include <errno.h>
#ifndef _DOUBLE_IS_32BITS
#ifdef __STDC__
double atanh(double x) /* wrapper atanh */
#else
double atanh(x) /* wrapper atanh */
double x;
#endif
{
#ifdef _IEEE_LIBM
return __ieee754_atanh(x);
#else
double z,y;
z = __ieee754_atanh(x);
if(_LIB_VERSION == _IEEE_ || isnan(x)) return z;
y = fabs(x);
if(y>=1.0) {
if(y>1.0) {
/* atanh(|x|>1) */
errno = EDOM;
return 0.0/0.0;
} else {
/* atanh(|x|=1) */
errno = EDOM;
return x/0.0; /* sign(x)*inf */
}
} else
return z;
#endif
}
#endif /* defined(_DOUBLE_IS_32BITS) */
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