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