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/* $NetBSD: cephes_subr.c,v 1.1 2007/08/20 16:01:33 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>
*/
#include <complex.h>
#include <math.h>
#include "cephes_subr.h"
/* calculate cosh and sinh */
void
_cchsh(double x, double *c, double *s)
{
double e, ei;
if (fabs(x) <= 0.5) {
*c = cosh(x);
*s = sinh(x);
} else {
e = exp(x);
ei = 0.5 / e;
e = 0.5 * e;
*s = e - ei;
*c = e + ei;
}
}
/* Program to subtract nearest integer multiple of PI */
/* extended precision value of PI: */
static const double DP1 = 3.14159265160560607910E0;
static const double DP2 = 1.98418714791870343106E-9;
static const double DP3 = 1.14423774522196636802E-17;
#define MACHEP 1.1e-16
double
_redupi(double x)
{
double t;
long i;
t = x / M_PI;
if (t >= 0.0)
t += 0.5;
else
t -= 0.5;
i = t; /* the multiple */
t = i;
t = ((x - t * DP1) - t * DP2) - t * DP3;
return t;
}
/* Taylor series expansion for cosh(2y) - cos(2x) */
double
_ctans(double complex z)
{
double f, x, x2, y, y2, rn, t;
double d;
x = fabs(2.0 * creal(z));
y = fabs(2.0 * cimag(z));
x = _redupi(x);
x = x * x;
y = y * y;
x2 = 1.0;
y2 = 1.0;
f = 1.0;
rn = 0.0;
d = 0.0;
do {
rn += 1.0;
f *= rn;
rn += 1.0;
f *= rn;
x2 *= x;
y2 *= y;
t = y2 + x2;
t /= f;
d += t;
rn += 1.0;
f *= rn;
rn += 1.0;
f *= rn;
x2 *= x;
y2 *= y;
t = y2 - x2;
t /= f;
d += t;
} while (fabs(t/d) > MACHEP);
return d;
}
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