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92 lines
3.0 KiB
C
92 lines
3.0 KiB
C
/* $NetBSD: clog.c,v 1.1 2007/08/20 16:01:35 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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* imported and modified include for newlib 2010/10/03
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* Marco Atzeri <marco_atzeri@yahoo.it>
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*/
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/*
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FUNCTION
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<<clog>>, <<clogf>>---complex base-e logarithm
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INDEX
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clog
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INDEX
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clogf
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ANSI_SYNOPSIS
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#include <complex.h>
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double complex clog(double complex <[z]>);
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float complex clogf(float complex <[z]>);
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DESCRIPTION
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These functions compute the complex natural (base-<[e]>) logarithm
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of <[z]>, with a branch cut along the negative real axis.
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<<clogf>> is identical to <<clog>>, except that it performs
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its calculations on <<floats complex>>.
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RETURNS
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@ifnottex
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The clog functions return the complex natural logarithm value, in
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the range of a strip mathematically unbounded along the real axis
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and in the interval [-i*pi , +i*pi] along the imaginary axis.
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@end ifnottex
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@tex
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The clog functions return the complex natural logarithm value, in
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the range of a strip mathematically unbounded along the real axis
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and in the interval [$-i\pi$, $+i\pi$] along the imaginary axis.
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@end tex
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PORTABILITY
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<<clog>> and <<clogf>> are ISO C99
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QUICKREF
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<<clog>> and <<clogf>> are ISO C99
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*/
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#include <complex.h>
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#include <math.h>
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double complex
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clog(double complex z)
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{
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double complex w;
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double p, rr;
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rr = cabs(z);
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p = log(rr);
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rr = atan2(cimag(z), creal(z));
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w = p + rr * I;
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return w;
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}
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