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 31public class Log10Tests { 32 private Log10Tests(){} 33 34 static final double infinityD = Double.POSITIVE_INFINITY; 35 static final double NaNd = Double.NaN; 36 static final double LN_10 = StrictMath.log(10.0); 37 38 // Initialize shared random number generator 39 static java.util.Random rand = new java.util.Random(0L); 40 41 static int testLog10Case(double input, double expected) { 42 int failures=0; 43 44 failures+=Tests.test("Math.log10(double)", input, 45 Math.log10(input), expected); 46 47 failures+=Tests.test("StrictMath.log10(double)", input, 48 StrictMath.log10(input), expected); 49 50 return failures; 51 } 52 53 static int testLog10() { 54 int failures = 0; 55 56 double [][] testCases = { 57 {Double.NaN, NaNd}, 58 {Double.longBitsToDouble(0x7FF0000000000001L), NaNd}, 59 {Double.longBitsToDouble(0xFFF0000000000001L), NaNd}, 60 {Double.longBitsToDouble(0x7FF8555555555555L), NaNd}, 61 {Double.longBitsToDouble(0xFFF8555555555555L), NaNd}, 62 {Double.longBitsToDouble(0x7FFFFFFFFFFFFFFFL), NaNd}, 63 {Double.longBitsToDouble(0xFFFFFFFFFFFFFFFFL), NaNd}, 64 {Double.longBitsToDouble(0x7FFDeadBeef00000L), NaNd}, 65 {Double.longBitsToDouble(0xFFFDeadBeef00000L), NaNd}, 66 {Double.longBitsToDouble(0x7FFCafeBabe00000L), NaNd}, 67 {Double.longBitsToDouble(0xFFFCafeBabe00000L), NaNd}, 68 {Double.NEGATIVE_INFINITY, NaNd}, 69 {-8.0, NaNd}, 70 {-1.0, NaNd}, 71 {-Double.MIN_NORMAL, NaNd}, 72 {-Double.MIN_VALUE, NaNd}, 73 {-0.0, -infinityD}, 74 {+0.0, -infinityD}, 75 {+1.0, 0.0}, 76 {Double.POSITIVE_INFINITY, infinityD}, 77 }; 78 79 // Test special cases 80 for(int i = 0; i < testCases.length; i++) { 81 failures += testLog10Case(testCases[i][0], 82 testCases[i][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 failures += 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)) > 3) { 110 failures++; 111 System.err.println("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(((result=StrictMath.log10(input)) - expected)/Math.ulp(expected)) > 3) { 118 failures++; 119 System.err.println("For input " + input + 120 ", StrictMath.log10 was more than 3 ulps different from " + 121 "log(input)/log(10): log10(input) = " + result + 122 "\tlog(input)/log(10) = " + expected); 123 } 124 125 126 } 127 } 128 } 129 130 // Test for accuracy and monotonicity near log10(1.0). From 131 // the Taylor expansion of log, 132 // log10(1+z) ~= (z -(z^2)/2)/LN_10; 133 { 134 double neighbors[] = new double[40]; 135 double neighborsStrict[] = new double[40]; 136 double z = Double.NaN; 137 138 // Test inputs greater than 1.0. 139 neighbors[0] = Math.log10(1.0); 140 neighborsStrict[0] = StrictMath.log10(1.0); 141 142 double input[] = new double[40]; 143 int half = input.length/2; 144 145 146 // 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 failures++; 173 System.err.println("For input near 1.0 " + input[i] + 174 ", Math.log10(1+z) was more than 3 ulps different from " + 175 "(z-(z^2)/2)/ln(10): log10(input) = " + neighbors[i] + 176 "\texpected about = " + expected); 177 } 178 179 if ( Math.abs(neighborsStrict[i] - expected ) > 3*Math.ulp(expected) ) { 180 failures++; 181 System.err.println("For input near 1.0 " + input[i] + 182 ", StrictMath.log10(1+z) was more than 3 ulps different from " + 183 "(z-(z^2)/2)/ln(10): log10(input) = " + neighborsStrict[i] + 184 "\texpected about = " + expected); 185 } 186 187 // Test monotonicity 188 if( i > 0) { 189 if( neighbors[i-1] > neighbors[i] ) { 190 failures++; 191 System.err.println("Monotonicity failure for Math.log10 at " + input[i] + 192 " and prior value."); 193 } 194 195 if( neighborsStrict[i-1] > neighborsStrict[i] ) { 196 failures++; 197 System.err.println("Monotonicity failure for StrictMath.log10 at " + input[i] + 198 " and prior value."); 199 } 200 } 201 } 202 203 } 204 205 return failures; 206 } 207 208 public static void main(String argv[]) { 209 int failures = 0; 210 211 failures += testLog10(); 212 213 if (failures > 0) { 214 System.err.println("Testing log10 incurred " 215 + failures + " failures."); 216 throw new RuntimeException(); 217 } 218 } 219 220} 221