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GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	lib/libm/src/s_csqrt.c	Lines:	0	32	0.0 %
Date:	2017-11-07	Branches:	0	14	0.0 %


/*	$OpenBSD: s_csqrt.c,v 1.8 2016/09/12 19:47:02 guenther Exp $	*/
/*
 * Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*							csqrt()
 *
 *	Complex square root
 *
 *
 *
 * SYNOPSIS:
 *
 * double complex csqrt();
 * double complex z, w;
 *
 * w = csqrt (z);
 *
 *
 *
 * DESCRIPTION:
 *
 *
 * If z = x + iy,  r = |z|, then
 *
 *                       1/2
 * Re w  =  [ (r + x)/2 ]   ,
 *
 *                       1/2
 * Im w  =  [ (r - x)/2 ]   .
 *
 * Cancellation error in r-x or r+x is avoided by using the
 * identity  2 Re w Im w  =  y.
 *
 * Note that -w is also a square root of z.  The root chosen
 * is always in the right half plane and Im w has the same sign as y.
 *
 *
 *
 * ACCURACY:
 *
 *                      Relative error:
 * arithmetic   domain     # trials      peak         rms
 *    DEC       -10,+10     25000       3.2e-17     9.6e-18
 *    IEEE      -10,+10   1,000,000     2.9e-16     6.1e-17
 *
 */

#include <complex.h>
#include <float.h>
#include <math.h>

double complex
csqrt(double complex z)
{
	double complex w;
	double x, y, r, t, scale;

	x = creal (z);
	y = cimag (z);

	if (y == 0.0) {
		if (x == 0.0) {
			w = 0.0 + y * I;
		}
		else {
			r = fabs (x);
			r = sqrt (r);
			if (x < 0.0) {
				w = 0.0 + copysign(r, y) * I;
			}
			else {
				w = r + y * I;
			}
		}
		return (w);
	}
	if (x == 0.0) {
		r = fabs (y);
		r = sqrt (0.5*r);
		if (y > 0)
			w = r + r * I;
		else
			w = r - r * I;
		return (w);
	}
	/* Rescale to avoid internal overflow or underflow.  */
	if ((fabs(x) > 4.0) || (fabs(y) > 4.0)) {
		x *= 0.25;
		y *= 0.25;
		scale = 2.0;
	}
	else {
		x *= 1.8014398509481984e16;  /* 2^54 */
		y *= 1.8014398509481984e16;
		scale = 7.450580596923828125e-9; /* 2^-27 */
#if 0
		x *= 4.0;
		y *= 4.0;
		scale = 0.5;
#endif
	}
	w = x + y * I;
	r = cabs(w);
	if (x > 0) {
		t = sqrt(0.5 * r + 0.5 * x);
		r = scale * fabs((0.5 * y) / t);
		t *= scale;
	}
	else {
		r = sqrt( 0.5 * r - 0.5 * x );
		t = scale * fabs( (0.5 * y) / r );
		r *= scale;
	}
	if (y < 0)
		w = t - r * I;
	else
		w = t + r * I;
	return (w);
}
DEF_STD(csqrt);
LDBL_MAYBE_CLONE(csqrt);


Generated by: GCOVR (Version 3.3)

Line	Branch	Exec	Source
1			/* $OpenBSD: s_csqrt.c,v 1.8 2016/09/12 19:47:02 guenther Exp $ */
2			/*
3			* Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net>
4			*
5			* Permission to use, copy, modify, and distribute this software for any
6			* purpose with or without fee is hereby granted, provided that the above
7			* copyright notice and this permission notice appear in all copies.
8			*
9			* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10			* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11			* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12			* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13			* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14			* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15			* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16			*/
17
18			/* csqrt()
19			*
20			* Complex square root
21			*
22			*
23			*
24			* SYNOPSIS:
25			*
26			* double complex csqrt();
27			* double complex z, w;
28			*
29			* w = csqrt (z);
30			*
31			*
32			*
33			* DESCRIPTION:
34			*
35			*
36			* If z = x + iy, r = \|z\|, then
37			*
38			* 1/2
39			* Re w = [ (r + x)/2 ] ,
40			*
41			* 1/2
42			* Im w = [ (r - x)/2 ] .
43			*
44			* Cancellation error in r-x or r+x is avoided by using the
45			* identity 2 Re w Im w = y.
46			*
47			* Note that -w is also a square root of z. The root chosen
48			* is always in the right half plane and Im w has the same sign as y.
49			*
50			*
51			*
52			* ACCURACY:
53			*
54			* Relative error:
55			* arithmetic domain # trials peak rms
56			* DEC -10,+10 25000 3.2e-17 9.6e-18
57			* IEEE -10,+10 1,000,000 2.9e-16 6.1e-17
58			*
59			*/
60
61			#include <complex.h>
62			#include <float.h>
63			#include <math.h>
64
65			double complex
66			csqrt(double complex z)
67			{
68			double complex w;
69			double x, y, r, t, scale;
70
71			x = creal (z);
72			y = cimag (z);
73
74			if (y == 0.0) {
75			if (x == 0.0) {
76			w = 0.0 + y * I;
77			}
78			else {
79			r = fabs (x);
80			r = sqrt (r);
81			if (x < 0.0) {
82			w = 0.0 + copysign(r, y) * I;
83			}
84			else {
85			w = r + y * I;
86			}
87			}
88			return (w);
89			}
90			if (x == 0.0) {
91			r = fabs (y);
92			r = sqrt (0.5*r);
93			if (y > 0)
94			w = r + r * I;
95			else
96			w = r - r * I;
97			return (w);
98			}
99			/* Rescale to avoid internal overflow or underflow. */
100			if ((fabs(x) > 4.0) \|\| (fabs(y) > 4.0)) {
101			x *= 0.25;
102			y *= 0.25;
103			scale = 2.0;
104			}
105			else {
106			x = 1.8014398509481984e16; / 2^54 */
107			y *= 1.8014398509481984e16;
108			scale = 7.450580596923828125e-9; /* 2^-27 */
109			#if 0
110			x *= 4.0;
111			y *= 4.0;
112			scale = 0.5;
113			#endif
114			}
115			w = x + y * I;
116			r = cabs(w);
117			if (x > 0) {
118			t = sqrt(0.5 * r + 0.5 * x);
119			r = scale * fabs((0.5 * y) / t);
120			t *= scale;
121			}
122			else {
123			r = sqrt( 0.5 * r - 0.5 * x );
124			t = scale * fabs( (0.5 * y) / r );
125			r *= scale;
126			}
127			if (y < 0)
128			w = t - r * I;
129			else
130			w = t + r * I;
131			return (w);
132			}
133			DEF_STD(csqrt);
134			LDBL_MAYBE_CLONE(csqrt);