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 }