1 /*
2 * Copyright (c) 2003, 2014, 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 4851638 4939441
27 * @summary Tests for {Math, StrictMath}.hypot
28 * @author Joseph D. Darcy
29 * @key randomness
30 */
31
32 public class HypotTests {
33 private HypotTests(){}
34
35 static final double infinityD = Double.POSITIVE_INFINITY;
36 static final double NaNd = Double.NaN;
37
38 /**
39 * Given integers m and n, assuming m < n, the triple (n^2 - m^2,
40 * 2mn, and n^2 + m^2) is a Pythagorean triple with a^2 + b^2 =
41 * c^2. This methods returns a long array holding the Pythagorean
42 * triple corresponding to the inputs.
43 */
44 static long [] pythagoreanTriple(int m, int n) {
45 long M = m;
46 long N = n;
47 long result[] = new long[3];
48
49
50 result[0] = Math.abs(M*M - N*N);
51 result[1] = Math.abs(2*M*N);
52 result[2] = Math.abs(M*M + N*N);
53
54 return result;
55 }
56
57 static int testHypot() {
58 int failures = 0;
59
60 double [][] testCases = {
61 // Special cases
62 {infinityD, infinityD, infinityD},
63 {infinityD, 0.0, infinityD},
64 {infinityD, 1.0, infinityD},
65 {infinityD, NaNd, infinityD},
66 {NaNd, NaNd, NaNd},
67 {0.0, NaNd, NaNd},
68 {1.0, NaNd, NaNd},
69 {Double.longBitsToDouble(0x7FF0000000000001L), 1.0, NaNd},
70 {Double.longBitsToDouble(0xFFF0000000000001L), 1.0, NaNd},
71 {Double.longBitsToDouble(0x7FF8555555555555L), 1.0, NaNd},
72 {Double.longBitsToDouble(0xFFF8555555555555L), 1.0, NaNd},
73 {Double.longBitsToDouble(0x7FFFFFFFFFFFFFFFL), 1.0, NaNd},
74 {Double.longBitsToDouble(0xFFFFFFFFFFFFFFFFL), 1.0, NaNd},
75 {Double.longBitsToDouble(0x7FFDeadBeef00000L), 1.0, NaNd},
76 {Double.longBitsToDouble(0xFFFDeadBeef00000L), 1.0, NaNd},
77 {Double.longBitsToDouble(0x7FFCafeBabe00000L), 1.0, NaNd},
78 {Double.longBitsToDouble(0xFFFCafeBabe00000L), 1.0, NaNd},
79 };
80
81 for(int i = 0; i < testCases.length; i++) {
82 failures += testHypotCase(testCases[i][0], testCases[i][1],
83 testCases[i][2]);
84 }
85
86 // Verify hypot(x, 0.0) is close to x over the entire exponent
87 // range.
88 for(int i = DoubleConsts.MIN_SUB_EXPONENT;
89 i <= Double.MAX_EXPONENT;
90 i++) {
91 double input = Math.scalb(2, i);
92 failures += testHypotCase(input, 0.0, input);
93 }
94
95
96 // Test Pythagorean triples
97
98 // Small ones
99 for(int m = 1; m < 10; m++) {
100 for(int n = m+1; n < 11; n++) {
101 long [] result = pythagoreanTriple(m, n);
102 failures += testHypotCase(result[0], result[1], result[2]);
103 }
104 }
105
106 // Big ones
107 for(int m = 100000; m < 100100; m++) {
108 for(int n = m+100000; n < 200200; n++) {
109 long [] result = pythagoreanTriple(m, n);
110 failures += testHypotCase(result[0], result[1], result[2]);
111 }
112 }
113
114 // Approaching overflow tests
115
116 /*
117 * Create a random value r with an large-ish exponent. The
118 * result of hypot(3*r, 4*r) should be approximately 5*r. (The
119 * computation of 4*r is exact since it just changes the
120 * exponent). While the exponent of r is less than or equal
121 * to (MAX_EXPONENT - 3), the computation should not overflow.
122 */
123 java.util.Random rand = new java.util.Random();
124 for(int i = 0; i < 1000; i++) {
125 double d = rand.nextDouble();
126 // Scale d to have an exponent equal to MAX_EXPONENT -15
127 d = Math.scalb(d, Double.MAX_EXPONENT
128 -15 - Tests.ilogb(d));
129 for(int j = 0; j <= 13; j += 1) {
130 failures += testHypotCase(3*d, 4*d, 5*d, 2.5);
131 d *= 2.0; // increase exponent by 1
132 }
133 }
134
135 // Test for monotonicity failures. Fix one argument and test
136 // two numbers before and two numbers after each chosen value;
137 // i.e.
138 //
139 // pcNeighbors[] =
140 // {nextDown(nextDown(pc)),
141 // nextDown(pc),
142 // pc,
143 // nextUp(pc),
144 // nextUp(nextUp(pc))}
145 //
146 // and we test that hypot(pcNeighbors[i]) <= hypot(pcNeighbors[i+1])
147 {
148 double pcNeighbors[] = new double[5];
149 double pcNeighborsHypot[] = new double[5];
150 double pcNeighborsStrictHypot[] = new double[5];
151
152
153 for(int i = -18; i <= 18; i++) {
154 double pc = Math.scalb(1.0, i);
155
156 pcNeighbors[2] = pc;
157 pcNeighbors[1] = Math.nextDown(pc);
158 pcNeighbors[0] = Math.nextDown(pcNeighbors[1]);
159 pcNeighbors[3] = Math.nextUp(pc);
160 pcNeighbors[4] = Math.nextUp(pcNeighbors[3]);
161
162 for(int j = 0; j < pcNeighbors.length; j++) {
163 pcNeighborsHypot[j] = Math.hypot(2.0, pcNeighbors[j]);
164 pcNeighborsStrictHypot[j] = StrictMath.hypot(2.0, pcNeighbors[j]);
165 }
166
167 for(int j = 0; j < pcNeighborsHypot.length-1; j++) {
168 if(pcNeighborsHypot[j] > pcNeighborsHypot[j+1] ) {
169 failures++;
170 System.err.println("Monotonicity failure for Math.hypot on " +
171 pcNeighbors[j] + " and " +
172 pcNeighbors[j+1] + "\n\treturned " +
173 pcNeighborsHypot[j] + " and " +
174 pcNeighborsHypot[j+1] );
175 }
176
177 if(pcNeighborsStrictHypot[j] > pcNeighborsStrictHypot[j+1] ) {
178 failures++;
179 System.err.println("Monotonicity failure for StrictMath.hypot on " +
180 pcNeighbors[j] + " and " +
181 pcNeighbors[j+1] + "\n\treturned " +
182 pcNeighborsStrictHypot[j] + " and " +
183 pcNeighborsStrictHypot[j+1] );
184 }
185
186
187 }
188
189 }
190 }
191
192
193 return failures;
194 }
195
196 static int testHypotCase(double input1, double input2, double expected) {
197 return testHypotCase(input1,input2, expected, 1);
198 }
199
200 static int testHypotCase(double input1, double input2, double expected,
201 double ulps) {
202 int failures = 0;
203 if (expected < 0.0) {
204 throw new AssertionError("Result of hypot must be greater than " +
205 "or equal to zero");
206 }
207
208 // Test Math and StrictMath methods with no inputs negated,
209 // each input negated singly, and both inputs negated. Also
210 // test inputs in reversed order.
211
212 for(int i = -1; i <= 1; i+=2) {
213 for(int j = -1; j <= 1; j+=2) {
214 double x = i * input1;
215 double y = j * input2;
216 failures += Tests.testUlpDiff("Math.hypot", x, y,
217 Math.hypot(x, y), expected, ulps);
218 failures += Tests.testUlpDiff("Math.hypot", y, x,
219 Math.hypot(y, x ), expected, ulps);
220
221 failures += Tests.testUlpDiff("StrictMath.hypot", x, y,
222 StrictMath.hypot(x, y), expected, ulps);
223 failures += Tests.testUlpDiff("StrictMath.hypot", y, x,
224 StrictMath.hypot(y, x), expected, ulps);
225 }
226 }
227
228 return failures;
229 }
230
231 public static void main(String argv[]) {
232 int failures = 0;
233
234 failures += testHypot();
235
236 if (failures > 0) {
237 System.err.println("Testing the hypot incurred "
238 + failures + " failures.");
239 throw new RuntimeException();
240 }
241 }
242
243 }