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