Branch data Line data Source code
1 : : /*-
2 : : * Copyright (c) 2007 David Schultz <das@FreeBSD.ORG>
3 : : * All rights reserved.
4 : : *
5 : : * Redistribution and use in source and binary forms, with or without
6 : : * modification, are permitted provided that the following conditions
7 : : * are met:
8 : : * 1. Redistributions of source code must retain the above copyright
9 : : * notice, this list of conditions and the following disclaimer.
10 : : * 2. Redistributions in binary form must reproduce the above copyright
11 : : * notice, this list of conditions and the following disclaimer in the
12 : : * documentation and/or other materials provided with the distribution.
13 : : *
14 : : * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 : : * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 : : * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 : : * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 : : * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 : : * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 : : * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 : : * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 : : * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 : : * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 : : * SUCH DAMAGE.
25 : : */
26 : :
27 : : #include "cdefs-compat.h"
28 : : //__FBSDID("$FreeBSD: src/lib/msun/src/s_csqrtf.c,v 1.3 2008/08/08 00:15:16 das Exp $");
29 : :
30 : : #include <openlibm_complex.h>
31 : : #include <openlibm_math.h>
32 : :
33 : : #include "math_private.h"
34 : :
35 : : /*
36 : : * gcc doesn't implement complex multiplication or division correctly,
37 : : * so we need to handle infinities specially. We turn on this pragma to
38 : : * notify conforming c99 compilers that the fast-but-incorrect code that
39 : : * gcc generates is acceptable, since the special cases have already been
40 : : * handled.
41 : : */
42 : : #ifndef __GNUC__
43 : : #pragma STDC CX_LIMITED_RANGE ON
44 : : #endif
45 : :
46 : : OLM_DLLEXPORT float complex
47 : 0 : csqrtf(float complex z)
48 : : {
49 : 0 : float a = crealf(z), b = cimagf(z);
50 : : double t;
51 : :
52 : : /* Handle special cases. */
53 [ # # ]: 0 : if (z == 0)
54 : 0 : return (CMPLXF(0, b));
55 [ # # ]: 0 : if (isinf(b))
56 : 0 : return (CMPLXF(INFINITY, b));
57 [ # # ]: 0 : if (isnan(a)) {
58 : 0 : t = (b - b) / (b - b); /* raise invalid if b is not a NaN */
59 : 0 : return (CMPLXF(a, t)); /* return NaN + NaN i */
60 : : }
61 [ # # ]: 0 : if (isinf(a)) {
62 : : /*
63 : : * csqrtf(inf + NaN i) = inf + NaN i
64 : : * csqrtf(inf + y i) = inf + 0 i
65 : : * csqrtf(-inf + NaN i) = NaN +- inf i
66 : : * csqrtf(-inf + y i) = 0 + inf i
67 : : */
68 [ # # ]: 0 : if (signbit(a))
69 : 0 : return (CMPLXF(fabsf(b - b), copysignf(a, b)));
70 : : else
71 : 0 : return (CMPLXF(a, copysignf(b - b, b)));
72 : : }
73 : : /*
74 : : * The remaining special case (b is NaN) is handled just fine by
75 : : * the normal code path below.
76 : : */
77 : :
78 : : /*
79 : : * We compute t in double precision to avoid overflow and to
80 : : * provide correct rounding in nearly all cases.
81 : : * This is Algorithm 312, CACM vol 10, Oct 1967.
82 : : */
83 [ # # ]: 0 : if (a >= 0) {
84 : 0 : t = sqrt((a + hypot(a, b)) * 0.5);
85 : 0 : return (CMPLXF(t, b / (2.0 * t)));
86 : : } else {
87 : 0 : t = sqrt((-a + hypot(a, b)) * 0.5);
88 : 0 : return (CMPLXF(fabsf(b) / (2.0 * t), copysignf(t, b)));
89 : : }
90 : : }
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