/* $NetBSD: catan.c,v 1.2 2011/07/03 06:45:24 mrg 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.
*/

#include "../src/namespace.h"
#include <complex.h>
#include <math.h>
#include <float.h>
#include "cephes_subr.h"

#ifdef __weak_alias
__weak_alias(catan, _catan)
#endif

#define MAXNUM DBL_MAX

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 = MAXNUM + MAXNUM * I;
       return w;
}