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_csqrt.c,v 1.4 2008/08/08 00:15:16 das Exp $");
29 : :
30 : : #include <float.h>
31 : : #include <openlibm_complex.h>
32 : : #include <openlibm_math.h>
33 : :
34 : : #include "math_private.h"
35 : :
36 : : /*
37 : : * gcc doesn't implement complex multiplication or division correctly,
38 : : * so we need to handle infinities specially. We turn on this pragma to
39 : : * notify conforming c99 compilers that the fast-but-incorrect code that
40 : : * gcc generates is acceptable, since the special cases have already been
41 : : * handled.
42 : : */
43 : : #ifndef __GNUC__
44 : : #pragma STDC CX_LIMITED_RANGE ON
45 : : #endif
46 : :
47 : : /* We risk spurious overflow for components >= DBL_MAX / (1 + sqrt(2)). */
48 : : #define THRESH 0x1.a827999fcef32p+1022
49 : :
50 : : OLM_DLLEXPORT double complex
51 : 0 : csqrt(double complex z)
52 : : {
53 : : double complex result;
54 : : double a, b;
55 : : double t;
56 : : int scale;
57 : :
58 : 0 : a = creal(z);
59 : 0 : b = cimag(z);
60 : :
61 : : /* Handle special cases. */
62 [ # # ]: 0 : if (z == 0)
63 : 0 : return (CMPLX(0, b));
64 [ # # ]: 0 : if (isinf(b))
65 : 0 : return (CMPLX(INFINITY, b));
66 [ # # ]: 0 : if (isnan(a)) {
67 : 0 : t = (b - b) / (b - b); /* raise invalid if b is not a NaN */
68 : 0 : return (CMPLX(a, t)); /* return NaN + NaN i */
69 : : }
70 [ # # ]: 0 : if (isinf(a)) {
71 : : /*
72 : : * csqrt(inf + NaN i) = inf + NaN i
73 : : * csqrt(inf + y i) = inf + 0 i
74 : : * csqrt(-inf + NaN i) = NaN +- inf i
75 : : * csqrt(-inf + y i) = 0 + inf i
76 : : */
77 [ # # ]: 0 : if (signbit(a))
78 : 0 : return (CMPLX(fabs(b - b), copysign(a, b)));
79 : : else
80 : 0 : return (CMPLX(a, copysign(b - b, b)));
81 : : }
82 : : /*
83 : : * The remaining special case (b is NaN) is handled just fine by
84 : : * the normal code path below.
85 : : */
86 : :
87 : : /* Scale to avoid overflow. */
88 [ # # # # ]: 0 : if (fabs(a) >= THRESH || fabs(b) >= THRESH) {
89 : 0 : a *= 0.25;
90 : 0 : b *= 0.25;
91 : 0 : scale = 1;
92 : : } else {
93 : 0 : scale = 0;
94 : : }
95 : :
96 : : /* Algorithm 312, CACM vol 10, Oct 1967. */
97 [ # # ]: 0 : if (a >= 0) {
98 : 0 : t = sqrt((a + hypot(a, b)) * 0.5);
99 : 0 : result = CMPLX(t, b / (2 * t));
100 : : } else {
101 : 0 : t = sqrt((-a + hypot(a, b)) * 0.5);
102 : 0 : result = CMPLX(fabs(b) / (2 * t), copysign(t, b));
103 : : }
104 : :
105 : : /* Rescale. */
106 [ # # ]: 0 : if (scale)
107 : 0 : return (result * 2);
108 : : else
109 : 0 : return (result);
110 : : }
111 : :
112 : : #if LDBL_MANT_DIG == 53
113 : : openlibm_weak_reference(csqrt, csqrtl);
114 : : #endif
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