1 | /* origin: FreeBSD /usr/src/lib/msun/src/s_cexpf.c */
|
---|
2 | /*-
|
---|
3 | * Copyright (c) 2011 David Schultz <das@FreeBSD.ORG>
|
---|
4 | * All rights reserved.
|
---|
5 | *
|
---|
6 | * Redistribution and use in source and binary forms, with or without
|
---|
7 | * modification, are permitted provided that the following conditions
|
---|
8 | * are met:
|
---|
9 | * 1. Redistributions of source code must retain the above copyright
|
---|
10 | * notice, this list of conditions and the following disclaimer.
|
---|
11 | * 2. Redistributions in binary form must reproduce the above copyright
|
---|
12 | * notice, this list of conditions and the following disclaimer in the
|
---|
13 | * documentation and/or other materials provided with the distribution.
|
---|
14 | *
|
---|
15 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
---|
16 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
---|
17 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
---|
18 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
---|
19 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
---|
20 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
---|
21 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
---|
22 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
---|
23 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
---|
24 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
---|
25 | * SUCH DAMAGE.
|
---|
26 | */
|
---|
27 |
|
---|
28 | #include "libm.h"
|
---|
29 |
|
---|
30 | static const uint32_t
|
---|
31 | exp_ovfl = 0x42b17218, /* MAX_EXP * ln2 ~= 88.722839355 */
|
---|
32 | cexp_ovfl = 0x43400074; /* (MAX_EXP - MIN_DENORM_EXP) * ln2 */
|
---|
33 |
|
---|
34 | float complex cexpf(float complex z)
|
---|
35 | {
|
---|
36 | float x, y, exp_x;
|
---|
37 | uint32_t hx, hy;
|
---|
38 |
|
---|
39 | x = crealf(z);
|
---|
40 | y = cimagf(z);
|
---|
41 |
|
---|
42 | GET_FLOAT_WORD(hy, y);
|
---|
43 | hy &= 0x7fffffff;
|
---|
44 |
|
---|
45 | /* cexp(x + I 0) = exp(x) + I 0 */
|
---|
46 | if (hy == 0)
|
---|
47 | return CMPLXF(expf(x), y);
|
---|
48 | GET_FLOAT_WORD(hx, x);
|
---|
49 | /* cexp(0 + I y) = cos(y) + I sin(y) */
|
---|
50 | if ((hx & 0x7fffffff) == 0)
|
---|
51 | return CMPLXF(cosf(y), sinf(y));
|
---|
52 |
|
---|
53 | if (hy >= 0x7f800000) {
|
---|
54 | if ((hx & 0x7fffffff) != 0x7f800000) {
|
---|
55 | /* cexp(finite|NaN +- I Inf|NaN) = NaN + I NaN */
|
---|
56 | return CMPLXF(y - y, y - y);
|
---|
57 | } else if (hx & 0x80000000) {
|
---|
58 | /* cexp(-Inf +- I Inf|NaN) = 0 + I 0 */
|
---|
59 | return CMPLXF(0.0, 0.0);
|
---|
60 | } else {
|
---|
61 | /* cexp(+Inf +- I Inf|NaN) = Inf + I NaN */
|
---|
62 | return CMPLXF(x, y - y);
|
---|
63 | }
|
---|
64 | }
|
---|
65 |
|
---|
66 | if (hx >= exp_ovfl && hx <= cexp_ovfl) {
|
---|
67 | /*
|
---|
68 | * x is between 88.7 and 192, so we must scale to avoid
|
---|
69 | * overflow in expf(x).
|
---|
70 | */
|
---|
71 | return __ldexp_cexpf(z, 0);
|
---|
72 | } else {
|
---|
73 | /*
|
---|
74 | * Cases covered here:
|
---|
75 | * - x < exp_ovfl and exp(x) won't overflow (common case)
|
---|
76 | * - x > cexp_ovfl, so exp(x) * s overflows for all s > 0
|
---|
77 | * - x = +-Inf (generated by exp())
|
---|
78 | * - x = NaN (spurious inexact exception from y)
|
---|
79 | */
|
---|
80 | exp_x = expf(x);
|
---|
81 | return CMPLXF(exp_x * cosf(y), exp_x * sinf(y));
|
---|
82 | }
|
---|
83 | }
|
---|