131 lines
3.6 KiB
C
131 lines
3.6 KiB
C
/* $NetBSD: catan.c,v 1.1 2007/08/20 16:01:32 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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<<catan>>, <<catanf>>---complex arc tangent
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INDEX
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catan
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INDEX
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catanf
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SYNOPSIS
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#include <complex.h>
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double complex catan(double complex <[z]>);
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float complex catanf(float complex <[z]>);
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DESCRIPTION
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@ifnottex
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These functions compute the complex arc tangent of <[z]>,
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with branch cuts outside the interval [-i, +i] along the
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imaginary axis.
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@end ifnottex
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@tex
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These functions compute the complex arc tangent of <[z]>,
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with branch cuts outside the interval [$-i$, $+i$] along the
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imaginary axis.
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@end tex
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<<catanf>> is identical to <<catan>>, 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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These functions return the complex arc tangent value, in the range
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of a strip mathematically unbounded along the imaginary axis
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and in the interval [-pi/2, +pi/2] along the real axis.
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@end ifnottex
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@tex
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These functions return the complex arc tangent, in the range
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of a strip mathematically unbounded along the imaginary axis
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and in the interval [$-\pi/2$, $+\pi/2$] along the real axis.
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@end tex
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PORTABILITY
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<<catan>> and <<catanf>> are ISO C99
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QUICKREF
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<<catan>> and <<catanf>> 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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#include "cephes_subr.h"
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#ifdef __weak_alias
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__weak_alias(catan, _catan)
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#endif
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double complex
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catan(double complex z)
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{
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double complex w;
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double a, t, x, x2, y;
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x = creal(z);
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y = cimag(z);
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if ((x == 0.0) && (y > 1.0))
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goto ovrf;
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x2 = x * x;
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a = 1.0 - x2 - (y * y);
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if (a == 0.0)
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goto ovrf;
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t = 0.5 * atan2(2.0 * x, a);
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w = _redupi(t);
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t = y - 1.0;
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a = x2 + (t * t);
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if (a == 0.0)
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goto ovrf;
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t = y + 1.0;
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a = (x2 + (t * t))/a;
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w = w + (0.25 * log(a)) * I;
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return w;
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ovrf:
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#if 0
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mtherr ("catan", OVERFLOW);
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#endif
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w = HUGE_VAL + HUGE_VAL * I;
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return w;
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}
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