1 /*
2 * Copyright (c) 2003, 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 * @library /test/lib
27 * @run main HypotTests
28 * @bug 4851638 4939441 8078672
29 * @summary Tests for {Math, StrictMath}.hypot (use -Dseed=X to set PRNG seed)
30 * @author Joseph D. Darcy
31 * @key randomness
32 */
33
34 import jdk.test.lib.RandomFactory;
35
36 public class HypotTests {
37 private HypotTests(){}
38
39 static final double infinityD = Double.POSITIVE_INFINITY;
40 static final double NaNd = Double.NaN;
41
42 /**
43 * Given integers m and n, assuming m < n, the triple (n^2 - m^2,
44 * 2mn, and n^2 + m^2) is a Pythagorean triple with a^2 + b^2 =
45 * c^2. This methods returns a long array holding the Pythagorean
46 * triple corresponding to the inputs.
47 */
48 static long [] pythagoreanTriple(int m, int n) {
49 long M = m;
50 long N = n;
51 long result[] = new long[3];
52
53
54 result[0] = Math.abs(M*M - N*N);
55 result[1] = Math.abs(2*M*N);
56 result[2] = Math.abs(M*M + N*N);
57
58 return result;
59 }
60
61 static int testHypot() {
62 int failures = 0;
63
64 double [][] testCases = {
65 // Special cases
66 {infinityD, infinityD, infinityD},
67 {infinityD, 0.0, infinityD},
68 {infinityD, 1.0, infinityD},
69 {infinityD, NaNd, infinityD},
70 {NaNd, NaNd, NaNd},
71 {0.0, NaNd, NaNd},
72 {1.0, NaNd, NaNd},
73 {Double.longBitsToDouble(0x7FF0000000000001L), 1.0, NaNd},
74 {Double.longBitsToDouble(0xFFF0000000000001L), 1.0, NaNd},
75 {Double.longBitsToDouble(0x7FF8555555555555L), 1.0, NaNd},
76 {Double.longBitsToDouble(0xFFF8555555555555L), 1.0, NaNd},
77 {Double.longBitsToDouble(0x7FFFFFFFFFFFFFFFL), 1.0, NaNd},
78 {Double.longBitsToDouble(0xFFFFFFFFFFFFFFFFL), 1.0, NaNd},
79 {Double.longBitsToDouble(0x7FFDeadBeef00000L), 1.0, NaNd},
80 {Double.longBitsToDouble(0xFFFDeadBeef00000L), 1.0, NaNd},
81 {Double.longBitsToDouble(0x7FFCafeBabe00000L), 1.0, NaNd},
82 {Double.longBitsToDouble(0xFFFCafeBabe00000L), 1.0, NaNd},
83 };
84
85 for(int i = 0; i < testCases.length; i++) {
86 failures += testHypotCase(testCases[i][0], testCases[i][1],
87 testCases[i][2]);
88 }
89
90 // Verify hypot(x, 0.0) is close to x over the entire exponent
91 // range.
92 for(int i = DoubleConsts.MIN_SUB_EXPONENT;
93 i <= Double.MAX_EXPONENT;
94 i++) {
95 double input = Math.scalb(2, i);
96 failures += testHypotCase(input, 0.0, input);
97 }
98
99
100 // Test Pythagorean triples
101
102 // Small ones
103 for(int m = 1; m < 10; m++) {
104 for(int n = m+1; n < 11; n++) {
105 long [] result = pythagoreanTriple(m, n);
106 failures += testHypotCase(result[0], result[1], result[2]);
107 }
108 }
109
110 // Big ones
111 for(int m = 100000; m < 100100; m++) {
112 for(int n = m+100000; n < 200200; n++) {
113 long [] result = pythagoreanTriple(m, n);
114 failures += testHypotCase(result[0], result[1], result[2]);
115 }
116 }
117
118 // Approaching overflow tests
119
120 /*
121 * Create a random value r with an large-ish exponent. The
122 * result of hypot(3*r, 4*r) should be approximately 5*r. (The
123 * computation of 4*r is exact since it just changes the
124 * exponent). While the exponent of r is less than or equal
125 * to (MAX_EXPONENT - 3), the computation should not overflow.
126 */
127 java.util.Random rand = RandomFactory.getRandom();
128 for(int i = 0; i < 1000; i++) {
129 double d = rand.nextDouble();
130 // Scale d to have an exponent equal to MAX_EXPONENT -15
131 d = Math.scalb(d, Double.MAX_EXPONENT
132 -15 - Tests.ilogb(d));
133 for(int j = 0; j <= 13; j += 1) {
134 failures += testHypotCase(3*d, 4*d, 5*d, 2.5);
135 d *= 2.0; // increase exponent by 1
136 }
137 }
138
139 // Test for monotonicity failures. Fix one argument and test
140 // two numbers before and two numbers after each chosen value;
141 // i.e.
142 //
143 // pcNeighbors[] =
144 // {nextDown(nextDown(pc)),
145 // nextDown(pc),
146 // pc,
147 // nextUp(pc),
148 // nextUp(nextUp(pc))}
149 //
150 // and we test that hypot(pcNeighbors[i]) <= hypot(pcNeighbors[i+1])
151 {
152 double pcNeighbors[] = new double[5];
153 double pcNeighborsHypot[] = new double[5];
154 double pcNeighborsStrictHypot[] = new double[5];
155
156
157 for(int i = -18; i <= 18; i++) {
158 double pc = Math.scalb(1.0, i);
159
160 pcNeighbors[2] = pc;
161 pcNeighbors[1] = Math.nextDown(pc);
162 pcNeighbors[0] = Math.nextDown(pcNeighbors[1]);
163 pcNeighbors[3] = Math.nextUp(pc);
164 pcNeighbors[4] = Math.nextUp(pcNeighbors[3]);
165
166 for(int j = 0; j < pcNeighbors.length; j++) {
167 pcNeighborsHypot[j] = Math.hypot(2.0, pcNeighbors[j]);
168 pcNeighborsStrictHypot[j] = StrictMath.hypot(2.0, pcNeighbors[j]);
169 }
170
171 for(int j = 0; j < pcNeighborsHypot.length-1; j++) {
172 if(pcNeighborsHypot[j] > pcNeighborsHypot[j+1] ) {
173 failures++;
174 System.err.println("Monotonicity failure for Math.hypot on " +
175 pcNeighbors[j] + " and " +
176 pcNeighbors[j+1] + "\n\treturned " +
177 pcNeighborsHypot[j] + " and " +
178 pcNeighborsHypot[j+1] );
179 }
180
181 if(pcNeighborsStrictHypot[j] > pcNeighborsStrictHypot[j+1] ) {
182 failures++;
183 System.err.println("Monotonicity failure for StrictMath.hypot on " +
184 pcNeighbors[j] + " and " +
185 pcNeighbors[j+1] + "\n\treturned " +
186 pcNeighborsStrictHypot[j] + " and " +
187 pcNeighborsStrictHypot[j+1] );
188 }
189
190
191 }
192
193 }
194 }
195
196
197 return failures;
198 }
199
200 static int testHypotCase(double input1, double input2, double expected) {
201 return testHypotCase(input1,input2, expected, 1);
202 }
203
204 static int testHypotCase(double input1, double input2, double expected,
205 double ulps) {
206 int failures = 0;
207 if (expected < 0.0) {
208 throw new AssertionError("Result of hypot must be greater than " +
209 "or equal to zero");
210 }
211
212 // Test Math and StrictMath methods with no inputs negated,
213 // each input negated singly, and both inputs negated. Also
214 // test inputs in reversed order.
215
216 for(int i = -1; i <= 1; i+=2) {
217 for(int j = -1; j <= 1; j+=2) {
218 double x = i * input1;
219 double y = j * input2;
220 failures += Tests.testUlpDiff("Math.hypot", x, y,
221 Math.hypot(x, y), expected, ulps);
222 failures += Tests.testUlpDiff("Math.hypot", y, x,
223 Math.hypot(y, x ), expected, ulps);
224
225 failures += Tests.testUlpDiff("StrictMath.hypot", x, y,
226 StrictMath.hypot(x, y), expected, ulps);
227 failures += Tests.testUlpDiff("StrictMath.hypot", y, x,
228 StrictMath.hypot(y, x), expected, ulps);
229 }
230 }
231
232 return failures;
233 }
234
235 public static void main(String argv[]) {
236 int failures = 0;
237
238 failures += testHypot();
239
240 if (failures > 0) {
241 System.err.println("Testing the hypot incurred "
242 + failures + " failures.");
243 throw new RuntimeException();
244 }
245 }
246
247 }