/newlib/libm/complex/catan.c
https://bitbucket.org/pizzafactory/binutils · C · 130 lines · 36 code · 13 blank · 81 comment · 7 complexity · b0d6204bf3926d5ce9878bc88829f855 MD5 · raw file
- /* $NetBSD: catan.c,v 1.1 2007/08/20 16:01:32 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>
- */
- /*
- FUNCTION
- <<catan>>, <<catanf>>---complex arc tangent
- INDEX
- catan
- INDEX
- catanf
- ANSI_SYNOPSIS
- #include <complex.h>
- double complex catan(double complex <[z]>);
- float complex catanf(float complex <[z]>);
- DESCRIPTION
- @ifnottex
- These functions compute the complex arc tangent of <[z]>,
- with branch cuts outside the interval [-i, +i] along the
- imaginary axis.
- @end ifnottex
- @tex
- These functions compute the complex arc tangent of <[z]>,
- with branch cuts outside the interval [$-i$, $+i$] along the
- imaginary axis.
- @end tex
- <<catanf>> is identical to <<catan>>, except that it performs
- its calculations on <<floats complex>>.
- RETURNS
- @ifnottex
- These functions return the complex arc tangent value, in the range
- of a strip mathematically unbounded along the imaginary axis
- and in the interval [-pi/2, +pi/2] along the real axis.
- @end ifnottex
- @tex
- These functions return the complex arc tangent, in the range
- of a strip mathematically unbounded along the imaginary axis
- and in the interval [$-\pi/2$, $+\pi/2$] along the real axis.
- @end tex
- PORTABILITY
- <<catan>> and <<catanf>> are ISO C99
- QUICKREF
- <<catan>> and <<catanf>> are ISO C99
- */
- #include <complex.h>
- #include <math.h>
- #include "cephes_subr.h"
- #ifdef __weak_alias
- __weak_alias(catan, _catan)
- #endif
- double complex
- catan(double complex z)
- {
- double complex w;
- double a, t, x, x2, y;
- x = creal(z);
- y = cimag(z);
- if ((x == 0.0) && (y > 1.0))
- goto ovrf;
- x2 = x * x;
- a = 1.0 - x2 - (y * y);
- if (a == 0.0)
- goto ovrf;
- t = 0.5 * atan2(2.0 * x, a);
- w = _redupi(t);
- t = y - 1.0;
- a = x2 + (t * t);
- if (a == 0.0)
- goto ovrf;
- t = y + 1.0;
- a = (x2 + (t * t))/a;
- w = w + (0.25 * log(a)) * I;
- return w;
- ovrf:
- #if 0
- mtherr ("catan", OVERFLOW);
- #endif
- w = HUGE_VAL + HUGE_VAL * I;
- return w;
- }