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