1 /*
2 * Copyright (c) 2003, 2015, 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 * @library /lib/testlibrary/
27 * @build jdk.testlibrary.*
28 * @run main HypotTests
29 * @bug 4851638 4939441 8078672
30 * @summary Tests for {Math, StrictMath}.hypot (use -Dseed=X to set PRNG seed)
31 * @author Joseph D. Darcy
32 * @key randomness
33 */
34
35 public class HypotTests {
36 private HypotTests(){}
37
38 static final double infinityD = Double.POSITIVE_INFINITY;
39 static final double NaNd = Double.NaN;
40
41 /**
42 * Given integers m and n, assuming m < n, the triple (n^2 - m^2,
43 * 2mn, and n^2 + m^2) is a Pythagorean triple with a^2 + b^2 =
44 * c^2. This methods returns a long array holding the Pythagorean
45 * triple corresponding to the inputs.
46 */
47 static long [] pythagoreanTriple(int m, int n) {
48 long M = m;
49 long N = n;
50 long result[] = new long[3];
51
52
53 result[0] = Math.abs(M*M - N*N);
54 result[1] = Math.abs(2*M*N);
55 result[2] = Math.abs(M*M + N*N);
56
57 return result;
58 }
59
60 static int testHypot() {
61 int failures = 0;
62
63 double [][] testCases = {
64 // Special cases
65 {infinityD, infinityD, infinityD},
66 {infinityD, 0.0, infinityD},
67 {infinityD, 1.0, infinityD},
68 {infinityD, NaNd, infinityD},
69 {NaNd, NaNd, NaNd},
70 {0.0, NaNd, NaNd},
71 {1.0, NaNd, NaNd},
72 {Double.longBitsToDouble(0x7FF0000000000001L), 1.0, NaNd},
73 {Double.longBitsToDouble(0xFFF0000000000001L), 1.0, NaNd},
74 {Double.longBitsToDouble(0x7FF8555555555555L), 1.0, NaNd},
75 {Double.longBitsToDouble(0xFFF8555555555555L), 1.0, NaNd},
76 {Double.longBitsToDouble(0x7FFFFFFFFFFFFFFFL), 1.0, NaNd},
77 {Double.longBitsToDouble(0xFFFFFFFFFFFFFFFFL), 1.0, NaNd},
78 {Double.longBitsToDouble(0x7FFDeadBeef00000L), 1.0, NaNd},
79 {Double.longBitsToDouble(0xFFFDeadBeef00000L), 1.0, NaNd},
80 {Double.longBitsToDouble(0x7FFCafeBabe00000L), 1.0, NaNd},
81 {Double.longBitsToDouble(0xFFFCafeBabe00000L), 1.0, NaNd},
82 };
83
84 for(int i = 0; i < testCases.length; i++) {
85 failures += testHypotCase(testCases[i][0], testCases[i][1],
86 testCases[i][2]);
87 }
88
89 // Verify hypot(x, 0.0) is close to x over the entire exponent
90 // range.
91 for(int i = DoubleConsts.MIN_SUB_EXPONENT;
92 i <= Double.MAX_EXPONENT;
93 i++) {
94 double input = Math.scalb(2, i);
95 failures += testHypotCase(input, 0.0, input);
96 }
97
98
99 // Test Pythagorean triples
100
101 // Small ones
102 for(int m = 1; m < 10; m++) {
103 for(int n = m+1; n < 11; n++) {
104 long [] result = pythagoreanTriple(m, n);
105 failures += testHypotCase(result[0], result[1], result[2]);
106 }
107 }
108
109 // Big ones
110 for(int m = 100000; m < 100100; m++) {
111 for(int n = m+100000; n < 200200; n++) {
112 long [] result = pythagoreanTriple(m, n);
113 failures += testHypotCase(result[0], result[1], result[2]);
114 }
115 }
116
117 // Approaching overflow tests
118
119 /*
120 * Create a random value r with an large-ish exponent. The
121 * result of hypot(3*r, 4*r) should be approximately 5*r. (The
122 * computation of 4*r is exact since it just changes the
123 * exponent). While the exponent of r is less than or equal
124 * to (MAX_EXPONENT - 3), the computation should not overflow.
125 */
126 java.util.Random rand = RandomFactory.getRandom();
127 for(int i = 0; i < 1000; i++) {
128 double d = rand.nextDouble();
129 // Scale d to have an exponent equal to MAX_EXPONENT -15
130 d = Math.scalb(d, Double.MAX_EXPONENT
131 -15 - Tests.ilogb(d));
132 for(int j = 0; j <= 13; j += 1) {
133 failures += testHypotCase(3*d, 4*d, 5*d, 2.5);
134 d *= 2.0; // increase exponent by 1
135 }
136 }
137
138 // Test for monotonicity failures. Fix one argument and test
139 // two numbers before and two numbers after each chosen value;
140 // i.e.
141 //
142 // pcNeighbors[] =
143 // {nextDown(nextDown(pc)),
144 // nextDown(pc),
145 // pc,
146 // nextUp(pc),
147 // nextUp(nextUp(pc))}
148 //
149 // and we test that hypot(pcNeighbors[i]) <= hypot(pcNeighbors[i+1])
150 {
151 double pcNeighbors[] = new double[5];
152 double pcNeighborsHypot[] = new double[5];
153 double pcNeighborsStrictHypot[] = new double[5];
154
155
156 for(int i = -18; i <= 18; i++) {
157 double pc = Math.scalb(1.0, i);
158
159 pcNeighbors[2] = pc;
160 pcNeighbors[1] = Math.nextDown(pc);
161 pcNeighbors[0] = Math.nextDown(pcNeighbors[1]);
162 pcNeighbors[3] = Math.nextUp(pc);
163 pcNeighbors[4] = Math.nextUp(pcNeighbors[3]);
164
165 for(int j = 0; j < pcNeighbors.length; j++) {
166 pcNeighborsHypot[j] = Math.hypot(2.0, pcNeighbors[j]);
167 pcNeighborsStrictHypot[j] = StrictMath.hypot(2.0, pcNeighbors[j]);
168 }
169
170 for(int j = 0; j < pcNeighborsHypot.length-1; j++) {
171 if(pcNeighborsHypot[j] > pcNeighborsHypot[j+1] ) {
172 failures++;
173 System.err.println("Monotonicity failure for Math.hypot on " +
174 pcNeighbors[j] + " and " +
175 pcNeighbors[j+1] + "\n\treturned " +
176 pcNeighborsHypot[j] + " and " +
177 pcNeighborsHypot[j+1] );
178 }
179
180 if(pcNeighborsStrictHypot[j] > pcNeighborsStrictHypot[j+1] ) {
181 failures++;
182 System.err.println("Monotonicity failure for StrictMath.hypot on " +
183 pcNeighbors[j] + " and " +
184 pcNeighbors[j+1] + "\n\treturned " +
185 pcNeighborsStrictHypot[j] + " and " +
186 pcNeighborsStrictHypot[j+1] );
187 }
188
189
190 }
191
192 }
193 }
194
195
196 return failures;
197 }
198
199 static int testHypotCase(double input1, double input2, double expected) {
200 return testHypotCase(input1,input2, expected, 1);
201 }
202
203 static int testHypotCase(double input1, double input2, double expected,
204 double ulps) {
205 int failures = 0;
206 if (expected < 0.0) {
207 throw new AssertionError("Result of hypot must be greater than " +
208 "or equal to zero");
209 }
210
211 // Test Math and StrictMath methods with no inputs negated,
212 // each input negated singly, and both inputs negated. Also
213 // test inputs in reversed order.
214
215 for(int i = -1; i <= 1; i+=2) {
216 for(int j = -1; j <= 1; j+=2) {
217 double x = i * input1;
218 double y = j * input2;
219 failures += Tests.testUlpDiff("Math.hypot", x, y,
220 Math.hypot(x, y), expected, ulps);
221 failures += Tests.testUlpDiff("Math.hypot", y, x,
222 Math.hypot(y, x ), expected, ulps);
223
224 failures += Tests.testUlpDiff("StrictMath.hypot", x, y,
225 StrictMath.hypot(x, y), expected, ulps);
226 failures += Tests.testUlpDiff("StrictMath.hypot", y, x,
227 StrictMath.hypot(y, x), expected, ulps);
228 }
229 }
230
231 return failures;
232 }
233
234 public static void main(String argv[]) {
235 int failures = 0;
236
237 failures += testHypot();
238
239 if (failures > 0) {
240 System.err.println("Testing the hypot incurred "
241 + failures + " failures.");
242 throw new RuntimeException();
243 }
244 }
245
246 }