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/* $NetBSD: csqrtf.c,v 1.1 2007/08/20 16:01:37 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>
*/
#include <complex.h>
#include <math.h>
float complex
csqrtf(float complex z)
{
float complex w;
float x, y, r, t, scale;
x = crealf(z);
y = cimagf(z);
if (y == 0.0f) {
if (x < 0.0f) {
w = 0.0f + sqrtf(-x) * I;
return w;
} else if (x == 0.0f) {
return (0.0f + y * I);
} else {
w = sqrtf(x) + y * I;
return w;
}
}
if (x == 0.0f) {
r = fabsf(y);
r = sqrtf(0.5f * r);
if (y > 0)
w = r + r * I;
else
w = r - r * I;
return w;
}
/* Rescale to avoid internal overflow or underflow. */
if ((fabsf(x) > 4.0f) || (fabsf(y) > 4.0f)) {
x *= 0.25f;
y *= 0.25f;
scale = 2.0f;
} else {
#if 1
x *= 6.7108864e7f; /* 2^26 */
y *= 6.7108864e7f;
scale = 1.220703125e-4f; /* 2^-13 */
#else
x *= 4.0f;
y *= 4.0f;
scale = 0.5f;
#endif
}
w = x + y * I;
r = cabsf(w);
if (x > 0) {
t = sqrtf(0.5f * r + 0.5f * x);
r = scale * fabsf((0.5f * y) / t);
t *= scale;
} else {
r = sqrtf(0.5f * r - 0.5f * x);
t = scale * fabsf((0.5f * y) / r);
r *= scale;
}
if (y < 0)
w = t - r * I;
else
w = t + r * I;
return w;
}
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