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/* $NetBSD: cephes_subrf.c,v 1.1 2007/08/20 16:01:34 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_subrf.h"
/* calculate cosh and sinh */
void
_cchshf(float x, float *c, float *s)
{
float e, ei;
if (fabsf(x) <= 0.5f) {
*c = coshf(x);
*s = sinhf(x);
} else {
e = expf(x);
ei = 0.5f / e;
e = 0.5f * e;
*s = e - ei;
*c = e + ei;
}
}
/* Program to subtract nearest integer multiple of PI */
/* extended precision value of PI: */
static const double DP1 = 3.140625;
static const double DP2 = 9.67502593994140625E-4;
static const double DP3 = 1.509957990978376432E-7;
#define MACHEPF 3.0e-8
float
_redupif(float x)
{
float t;
long i;
t = x / (float)M_PI;
if (t >= 0.0f)
t += 0.5f;
else
t -= 0.5f;
i = t; /* the multiple */
t = i;
t = ((x - t * DP1) - t * DP2) - t * DP3;
return t;
}
/* Taylor series expansion for cosh(2y) - cos(2x) */
float
_ctansf(float complex z)
{
float f, x, x2, y, y2, rn, t, d;
x = fabsf(2.0f * crealf(z));
y = fabsf(2.0f * cimagf(z));
x = _redupif(x);
x = x * x;
y = y * y;
x2 = 1.0f;
y2 = 1.0f;
f = 1.0f;
rn = 0.0f;
d = 0.0f;
do {
rn += 1.0f;
f *= rn;
rn += 1.0f;
f *= rn;
x2 *= x;
y2 *= y;
t = y2 + x2;
t /= f;
d += t;
rn += 1.0f;
f *= rn;
rn += 1.0f;
f *= rn;
x2 *= x;
y2 *= y;
t = y2 - x2;
t /= f;
d += t;
} while (fabsf(t/d) > MACHEPF);
return d;
}
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