1 /*
2 * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24 /*
25 * @test
26 * @bug 8139688
27 * @key randomness
28 * @library /test/lib
29 * @build Tests
30 * @build FdlibmTranslit
31 * @build ExpTests
32 * @run main ExpTests
33 * @summary Tests specifically for StrictMath.exp
34 */
35
36 import jdk.test.lib.RandomFactory;
37
38 /**
39 * The role of this test is to verify that the FDLIBM exp algorithm is
40 * being used by running golden file style tests on values that may
41 * vary from one conforming exponential implementation to another.
42 */
43
44 public class ExpTests {
45 private ExpTests(){}
46
47 public static void main(String [] argv) {
48 int failures = 0;
49
50 failures += testExp();
51 failures += testAgainstTranslit();
52
53 if (failures > 0) {
54 System.err.println("Testing the exponential incurred "
55 + failures + " failures.");
56 throw new RuntimeException();
57 }
58 }
59
60 // From the fdlibm source, the overflow threshold in hex is:
61 // 0x4086_2E42_FEFA_39EF.
62 static final double EXP_OVERFLOW_THRESH = Double.longBitsToDouble(0x4086_2E42_FEFA_39EFL);
63
64 // From the fdlibm source, the underflow threshold in hex is:
65 // 0xc087_4910_D52D_3051L.
66 static final double EXP_UNDERFLOW_THRESH = Double.longBitsToDouble(0xc087_4910_D52D_3051L);
67
68 static int testExp() {
69 int failures = 0;
70
71 double [][] testCases = {
72 // Some of these could be moved to common Math/StrictMath exp testing.
73 {Double.NaN, Double.NaN},
74 {Double.MAX_VALUE, Double.POSITIVE_INFINITY},
75 {Double.POSITIVE_INFINITY, Double.POSITIVE_INFINITY},
76 {Double.NEGATIVE_INFINITY, +0.0},
77 {EXP_OVERFLOW_THRESH, 0x1.ffff_ffff_fff2ap1023},
78 {Math.nextUp(EXP_OVERFLOW_THRESH), Double.POSITIVE_INFINITY},
79 {Math.nextDown(EXP_UNDERFLOW_THRESH), +0.0},
80 {EXP_UNDERFLOW_THRESH, +Double.MIN_VALUE},
81 };
82
83 for(double[] testCase: testCases)
84 failures+=testExpCase(testCase[0], testCase[1]);
85
86 return failures;
87 }
88
89 static int testExpCase(double input, double expected) {
90 int failures = 0;
91
92 failures+=Tests.test("StrictMath.exp(double)", input,
93 StrictMath.exp(input), expected);
94 return failures;
95 }
96
97 // Initialize shared random number generator
98 private static java.util.Random random = RandomFactory.getRandom();
99
100 /**
101 * Test StrictMath.exp against transliteration port of exp.
102 */
103 private static int testAgainstTranslit() {
104 int failures = 0;
105
106 double[] decisionPoints = {
107 // Near overflow threshold
108 EXP_OVERFLOW_THRESH - 512*Math.ulp(EXP_OVERFLOW_THRESH),
109
110 // Near underflow threshold
111 EXP_UNDERFLOW_THRESH - 512*Math.ulp(EXP_UNDERFLOW_THRESH),
112
113 // Straddle algorithm conditional checks
114 Double.longBitsToDouble(0x4086_2E42_0000_0000L - 512L),
115 Double.longBitsToDouble(0x3fd6_2e42_0000_0000L - 512L),
116 Double.longBitsToDouble(0x3FF0_A2B2_0000_0000L - 512L),
117 Double.longBitsToDouble(0x3e30_0000_0000_0000L - 512L),
118
119 // Other notable points
120 Double.MIN_NORMAL - Math.ulp(Double.MIN_NORMAL)*512,
121 -Double.MIN_VALUE*512,
122 };
123
124 for (double decisionPoint : decisionPoints) {
125 double ulp = Math.ulp(decisionPoint);
126 failures += testRange(decisionPoint - 1024*ulp, ulp, 1_024);
127 }
128
129 // Try out some random values
130 for (int i = 0; i < 100; i++) {
131 double x = Tests.createRandomDouble(random);
132 failures += testRange(x, Math.ulp(x), 100);
133 }
134
135 return failures;
136 }
137
138 private static int testRange(double start, double increment, int count) {
139 int failures = 0;
140 double x = start;
141 for (int i = 0; i < count; i++, x += increment) {
142 failures += testExpCase(x, FdlibmTranslit.Exp.compute(x));
143 }
144 return failures;
145 }
146 }