Retro68/gcc/newlib/libm/complex/cacosh.c

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/* $NetBSD: cacosh.c,v 1.2 2009/08/03 19:41:32 drochner Exp $ */
/*-
* Copyright (c) 2007 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software written by Stephen L. Moshier.
* It is redistributed by the NetBSD Foundation by permission of the author.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* imported and modified include for newlib 2010/10/03
* Marco Atzeri <marco_atzeri@yahoo.it>
*/
/*
FUNCTION
<<cacosh>>, <<cacoshf>>---complex arc hyperbolic cosine
INDEX
cacosh
INDEX
cacoshf
ANSI_SYNOPSIS
#include <complex.h>
double complex cacosh(double complex <[z]>);
float complex cacoshf(float complex <[z]>);
DESCRIPTION
These functions compute the complex arc hyperbolic cosine of <[z]>,
with a branch cut at values less than 1 along the real axis.
<<cacoshf>> is identical to <<cacosh>>, except that it performs
its calculations on <<floats complex>>.
RETURNS
@ifnottex
These functions return the complex arc hyperbolic cosine value,
in the range of a half-strip of non-negative values along the
real axis and in the interval [-i * pi, +i * pi] along the
imaginary axis.
@end ifnottex
@tex
These functions return the complex arc hyperbolic cosine value,
in the range of a half-strip of non-negative values along the
real axis and in the interval [$-i\pi$, $+i\pi$] along the
imaginary axis.
@end tex
PORTABILITY
<<cacosh>> and <<cacoshf>> are ISO C99
QUICKREF
<<cacosh>> and <<cacoshf>> are ISO C99
*/
#include <complex.h>
double complex
cacosh(double complex z)
{
double complex w;
#if 0 /* does not give the principal value */
w = I * cacos(z);
#else
w = clog(z + csqrt(z + 1) * csqrt(z - 1));
#endif
return w;
}