/* $NetBSD: casinf.c,v 1.1 2007/08/20 16:01:31 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.
*/

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

#ifdef __weak_alias
__weak_alias(casinf, _casinf)
#endif

float complex
casinf(float complex z)
{
       float complex w;
       float complex ca, ct, zz, z2;
       float x, y;

       x = crealf(z);
       y = cimagf(z);

#if 0 /* MD: test is incorrect, casin(>1) is defined */
       if (y == 0.0f) {
               if (fabsf(x) > 1.0) {
                       w = M_PI_2 + 0.0f * I;
#if 0
                       mtherr ("casin", DOMAIN);
#endif
               } else {
                       w = asinf(x) + 0.0f * I;
               }
               return w;
       }
#endif

/* Power series expansion */
/*
b = cabsf(z);
if( b < 0.125 )
{
z2.r = (x - y) * (x + y);
z2.i = 2.0 * x * y;

cn = 1.0;
n = 1.0;
ca.r = x;
ca.i = y;
sum.r = x;
sum.i = y;
do
       {
       ct.r = z2.r * ca.r  -  z2.i * ca.i;
       ct.i = z2.r * ca.i  +  z2.i * ca.r;
       ca.r = ct.r;
       ca.i = ct.i;

       cn *= n;
       n += 1.0;
       cn /= n;
       n += 1.0;
       b = cn/n;

       ct.r *= b;
       ct.i *= b;
       sum.r += ct.r;
       sum.i += ct.i;
       b = fabsf(ct.r) + fabsf(ct.i);
       }
while( b > MACHEP );
w->r = sum.r;
w->i = sum.i;
return;
}
*/


       ca = x + y * I;
       ct = ca * I;
       /* sqrt( 1 - z*z) */
       /* cmul( &ca, &ca, &zz ) */
       /*x * x  -  y * y */
       zz = (x - y) * (x + y) + (2.0f * x * y) * I;

       zz = 1.0f - crealf(zz) - cimagf(zz) * I;
       z2 = csqrtf(zz);

       zz = ct + z2;
       zz = clogf(zz);
       /* multiply by 1/i = -i */
       w = zz * (-1.0f * I);
       return w;
}