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11175 libm should use signbit() correctly
11188 c99 math macros should return strictly backward compatible values
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--- old/usr/src/lib/libm/common/C/tanh.c
+++ new/usr/src/lib/libm/common/C/tanh.c
1 1 /*
2 2 * CDDL HEADER START
3 3 *
4 4 * The contents of this file are subject to the terms of the
5 5 * Common Development and Distribution License (the "License").
6 6 * You may not use this file except in compliance with the License.
7 7 *
8 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 9 * or http://www.opensolaris.org/os/licensing.
10 10 * See the License for the specific language governing permissions
11 11 * and limitations under the License.
12 12 *
13 13 * When distributing Covered Code, include this CDDL HEADER in each
14 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 15 * If applicable, add the following below this CDDL HEADER, with the
16 16 * fields enclosed by brackets "[]" replaced with your own identifying
17 17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 18 *
19 19 * CDDL HEADER END
20 20 */
21 21
22 22 /*
23 23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
24 24 */
25 25 /*
26 26 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
27 27 * Use is subject to license terms.
28 28 */
29 29
30 30 #pragma weak __tanh = tanh
31 31
32 32 /* INDENT OFF */
33 33 /*
34 34 * TANH(X)
35 35 * RETURN THE HYPERBOLIC TANGENT OF X
36 36 * code based on 4.3bsd
37 37 * Modified by K.C. Ng for sun 4.0, Jan 31, 1987
38 38 *
39 39 * Method :
40 40 * 1. reduce x to non-negative by tanh(-x) = - tanh(x).
41 41 * 2.
42 42 * 0 < x <= 1.e-10 : tanh(x) := x
43 43 * -expm1(-2x)
44 44 * 1.e-10 < x <= 1 : tanh(x) := --------------
45 45 * expm1(-2x) + 2
46 46 * 2
47 47 * 1 <= x <= 22.0 : tanh(x) := 1 - ---------------
48 48 * expm1(2x) + 2
49 49 * 22.0 < x <= INF : tanh(x) := 1.
50 50 *
51 51 * Note: 22 was chosen so that fl(1.0+2/(expm1(2*22)+2)) == 1.
52 52 *
53 53 * Special cases:
54 54 * tanh(NaN) is NaN;
55 55 * only tanh(0)=0 is exact for finite argument.
56 56 */
57 57
58 58 #include "libm.h"
59 59 #include "libm_protos.h"
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60 60 #include <math.h>
61 61
62 62 static const double
63 63 one = 1.0,
64 64 two = 2.0,
65 65 small = 1.0e-10,
66 66 big = 1.0e10;
67 67 /* INDENT ON */
68 68
69 69 double
70 -tanh(double x) {
70 +tanh(double x)
71 +{
71 72 double t, y, z;
72 73 int signx;
73 74 volatile double dummy __unused;
74 75
75 76 if (isnan(x))
76 77 return (x * x); /* + -> * for Cheetah */
77 78 signx = signbit(x);
78 79 t = fabs(x);
79 80 z = one;
80 81 if (t <= 22.0) {
81 82 if (t > one)
82 83 z = one - two / (expm1(t + t) + two);
83 84 else if (t > small) {
84 85 y = expm1(-t - t);
85 86 z = -y / (y + two);
86 87 } else {
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87 88 /* raise the INEXACT flag for non-zero t */
88 89 dummy = t + big;
89 90 #ifdef lint
90 91 dummy = dummy;
91 92 #endif
92 93 return (x);
93 94 }
94 95 } else if (!finite(t))
95 96 return (copysign(1.0, x));
96 97 else
97 - return (signx == 1 ? -z + small * small : z - small * small);
98 + return ((signx != 0) ? -z + small * small : z - small * small);
98 99
99 - return (signx == 1 ? -z : z);
100 + return ((signx != 0) ? -z : z);
100 101 }
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