124 lines
2.9 KiB
C
124 lines
2.9 KiB
C
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/* $NetBSD: cephes_subrf.c,v 1.1 2007/08/20 16:01:34 drochner Exp $ */
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/*-
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* Copyright (c) 2007 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software written by Stephen L. Moshier.
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* It is redistributed by the NetBSD Foundation by permission of the author.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "../src/namespace.h"
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#include <complex.h>
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#include <math.h>
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#include "cephes_subrf.h"
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/* calculate cosh and sinh */
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void
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_cchshf(float x, float *c, float *s)
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{
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float e, ei;
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if (fabsf(x) <= 0.5f) {
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*c = coshf(x);
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*s = sinhf(x);
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} else {
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e = expf(x);
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ei = 0.5f / e;
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e = 0.5f * e;
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*s = e - ei;
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*c = e + ei;
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}
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}
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/* Program to subtract nearest integer multiple of PI */
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/* extended precision value of PI: */
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static const double DP1 = 3.140625;
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static const double DP2 = 9.67502593994140625E-4;
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static const double DP3 = 1.509957990978376432E-7;
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#define MACHEPF 3.0e-8
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float
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_redupif(float x)
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{
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float t;
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long i;
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t = x / (float)M_PI;
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if (t >= 0.0f)
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t += 0.5f;
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else
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t -= 0.5f;
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i = t; /* the multiple */
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t = i;
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t = ((x - t * DP1) - t * DP2) - t * DP3;
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return t;
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}
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/* Taylor series expansion for cosh(2y) - cos(2x) */
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float
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_ctansf(float complex z)
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{
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float f, x, x2, y, y2, rn, t, d;
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x = fabsf(2.0f * crealf(z));
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y = fabsf(2.0f * cimagf(z));
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x = _redupif(x);
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x = x * x;
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y = y * y;
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x2 = 1.0f;
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y2 = 1.0f;
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f = 1.0f;
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rn = 0.0f;
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d = 0.0f;
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do {
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rn += 1.0f;
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f *= rn;
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rn += 1.0f;
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f *= rn;
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x2 *= x;
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y2 *= y;
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t = y2 + x2;
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t /= f;
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d += t;
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rn += 1.0f;
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f *= rn;
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rn += 1.0f;
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f *= rn;
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x2 *= x;
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y2 *= y;
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t = y2 - x2;
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t /= f;
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d += t;
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} while (fabsf(t/d) > MACHEPF);
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return d;
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}
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