mirror of https://gitlab.com/rnger/amath
76 lines
2.5 KiB
C
76 lines
2.5 KiB
C
/* $NetBSD: ctan.c,v 1.1 2007/08/20 16:01:37 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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* The origin source code can be obtained from:
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* http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libm/complex/ctan.c?rev=1.1
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*
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*/
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#include "prim.h"
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#include "math.h"
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#include "complex.h"
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/**
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* @brief Tangent of a complex number
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* @version 1.1
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* @date 2007/08/20
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* @details
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* Calculated as in Open Office:<BR>
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* https://wiki.openoffice.org/wiki/Documentation/How_Tos/Calc:_IMTAN_function
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* <pre>
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* a+bi
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* sin(2.0 * a)
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* real = ------------------------------
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* cos(2.0 * a) + cosh(2.0 * b)
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*
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* sinh(2.0 * b)
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* imag = ------------------------------
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* cos(2.0 * a) + cosh(2.0 * b)
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* </pre>
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*/
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complex ctan(complex z)
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{
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complex w;
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double a, b;
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double d;
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a = creal(z);
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b = cimag(z);
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d = cos(2.0 * a) + cosh(2.0 * b);
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if (d == 0.0) {
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w = cpack(HUGE, HUGE); // TODO: INF, INF
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} else {
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w = cpack((sin(2.0 * a) / d), (sinh(2.0 * b) / d));
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}
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return w;
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}
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