1 /* 2 * Copyright (c) 2003, 2012, 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 4074599 4939441 27 * @summary Tests for {Math, StrictMath}.log10 28 * @author Joseph D. Darcy 29 */ 30 package test.java.lang.Math; 31 32 import org.testng.annotations.Test; 33 import org.testng.Assert; 34 35 public class Log10Tests { 36 Log10Tests()37 private Log10Tests() { 38 } 39 40 static final double infinityD = Double.POSITIVE_INFINITY; 41 static final double NaNd = Double.NaN; 42 static final double LN_10 = StrictMath.log(10.0); 43 44 // Initialize shared random number generator 45 static java.util.Random rand = new java.util.Random(0L); 46 testLog10Case(double input, double expected)47 static void testLog10Case(double input, double expected) { 48 Tests.test("Math.log10(double)", input, 49 Math.log10(input), expected); 50 51 Tests.test("StrictMath.log10(double)", input, 52 StrictMath.log10(input), expected); 53 } 54 55 @Test testLog10()56 public void testLog10() { 57 double[][] testCases = { 58 {Double.NaN, NaNd}, 59 {Double.longBitsToDouble(0x7FF0000000000001L), NaNd}, 60 {Double.longBitsToDouble(0xFFF0000000000001L), NaNd}, 61 {Double.longBitsToDouble(0x7FF8555555555555L), NaNd}, 62 {Double.longBitsToDouble(0xFFF8555555555555L), NaNd}, 63 {Double.longBitsToDouble(0x7FFFFFFFFFFFFFFFL), NaNd}, 64 {Double.longBitsToDouble(0xFFFFFFFFFFFFFFFFL), NaNd}, 65 {Double.longBitsToDouble(0x7FFDeadBeef00000L), NaNd}, 66 {Double.longBitsToDouble(0xFFFDeadBeef00000L), NaNd}, 67 {Double.longBitsToDouble(0x7FFCafeBabe00000L), NaNd}, 68 {Double.longBitsToDouble(0xFFFCafeBabe00000L), NaNd}, 69 {Double.NEGATIVE_INFINITY, NaNd}, 70 {-8.0, NaNd}, 71 {-1.0, NaNd}, 72 {-Double.MIN_NORMAL, NaNd}, 73 {-Double.MIN_VALUE, NaNd}, 74 {-0.0, -infinityD}, 75 {+0.0, -infinityD}, 76 {+1.0, 0.0}, 77 {Double.POSITIVE_INFINITY, infinityD}, 78 }; 79 80 // Test special cases 81 for (double[] aCase : testCases) { 82 testLog10Case(aCase[0], aCase[1]); 83 } 84 85 // Test log10(10^n) == n for integer n; 10^n, n < 0 is not 86 // exactly representable as a floating-point value -- up to 87 // 10^22 can be represented exactly 88 double testCase = 1.0; 89 for (int i = 0; i < 23; i++) { 90 testLog10Case(testCase, i); 91 testCase *= 10.0; 92 } 93 94 // Test for gross inaccuracy by comparing to log; should be 95 // within a few ulps of log(x)/log(10) 96 for (int i = 0; i < 10000; i++) { 97 double input = Double.longBitsToDouble(rand.nextLong()); 98 if (!Double.isFinite(input)) { 99 continue; // avoid testing NaN and infinite values 100 } else { 101 input = Math.abs(input); 102 103 double expected = StrictMath.log(input) / LN_10; 104 if (!Double.isFinite(expected)) { 105 continue; // if log(input) overflowed, try again 106 } else { 107 double result; 108 109 if (Math.abs(((result = Math.log10(input)) - expected) / Math.ulp(expected)) 110 > 3) { 111 Assert.fail("For input " + input + 112 ", Math.log10 was more than 3 ulps different from " + 113 "log(input)/log(10): log10(input) = " + result + 114 "\tlog(input)/log(10) = " + expected); 115 } 116 117 if (Math.abs( 118 ((result = StrictMath.log10(input)) - expected) / Math.ulp(expected)) 119 > 3) { 120 Assert.fail("For input " + input + 121 ", StrictMath.log10 was more than 3 ulps different from " + 122 "log(input)/log(10): log10(input) = " + result + 123 "\tlog(input)/log(10) = " + expected); 124 } 125 126 127 } 128 } 129 } 130 131 // Test for accuracy and monotonicity near log10(1.0). From 132 // the Taylor expansion of log, 133 // log10(1+z) ~= (z -(z^2)/2)/LN_10; 134 { 135 double[] neighbors = new double[40]; 136 double[] neighborsStrict = new double[40]; 137 double z = Double.NaN; 138 139 // Test inputs greater than 1.0. 140 neighbors[0] = Math.log10(1.0); 141 neighborsStrict[0] = StrictMath.log10(1.0); 142 143 double[] input = new double[40]; 144 int half = input.length / 2; 145 146 // Initialize input to the 40 consecutive double values 147 // "centered" at 1.0. 148 double up = Double.NaN; 149 double down = Double.NaN; 150 for (int i = 0; i < half; i++) { 151 if (i == 0) { 152 input[half] = 1.0; 153 up = Math.nextUp(1.0); 154 down = Math.nextDown(1.0); 155 } else { 156 input[half + i] = up; 157 input[half - i] = down; 158 up = Math.nextUp(up); 159 down = Math.nextDown(down); 160 } 161 } 162 input[0] = Math.nextDown(input[1]); 163 164 for (int i = 0; i < neighbors.length; i++) { 165 neighbors[i] = Math.log10(input[i]); 166 neighborsStrict[i] = StrictMath.log10(input[i]); 167 168 // Test accuracy. 169 z = input[i] - 1.0; 170 double expected = (z - (z * z) * 0.5) / LN_10; 171 if (Math.abs(neighbors[i] - expected) > 3 * Math.ulp(expected)) { 172 Assert.fail("For input near 1.0 " + input[i] + 173 ", Math.log10(1+z) was more than 3 ulps different from " + 174 "(z-(z^2)/2)/ln(10): log10(input) = " + neighbors[i] + 175 "\texpected about = " + expected); 176 } 177 178 if (Math.abs(neighborsStrict[i] - expected) > 3 * Math.ulp(expected)) { 179 Assert.fail("For input near 1.0 " + input[i] + 180 ", StrictMath.log10(1+z) was more than 3 ulps different from " + 181 "(z-(z^2)/2)/ln(10): log10(input) = " + neighborsStrict[i] + 182 "\texpected about = " + expected); 183 } 184 185 // Test monotonicity 186 if (i > 0) { 187 if (neighbors[i - 1] > neighbors[i]) { 188 Assert.fail("Monotonicity failure for Math.log10 at " + input[i] + 189 " and prior value."); 190 } 191 192 if (neighborsStrict[i - 1] > neighborsStrict[i]) { 193 Assert.fail("Monotonicity failure for StrictMath.log10 at " + input[i] + 194 " and prior value."); 195 } 196 } 197 } 198 199 } 200 } 201 } 202