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 31 import sun.misc.DoubleConsts; 32 33 public class Log10Tests { 34 private Log10Tests(){} 35 36 static final double infinityD = Double.POSITIVE_INFINITY; 37 static final double NaNd = Double.NaN; 38 static final double LN_10 = StrictMath.log(10.0); 39 40 // Initialize shared random number generator 41 static java.util.Random rand = new java.util.Random(0L); 42 43 static int testLog10Case(double input, double expected) { 44 int failures=0; 45 46 failures+=Tests.test("Math.log10(double)", input, 47 Math.log10(input), expected); 48 49 failures+=Tests.test("StrictMath.log10(double)", input, 50 StrictMath.log10(input), expected); 51 52 return failures; 53 } 54 55 static int testLog10() { 56 int failures = 0; 57 58 double [][] testCases = { 59 {Double.NaN, NaNd}, 60 {Double.longBitsToDouble(0x7FF0000000000001L), NaNd}, 61 {Double.longBitsToDouble(0xFFF0000000000001L), NaNd}, 62 {Double.longBitsToDouble(0x7FF8555555555555L), NaNd}, 63 {Double.longBitsToDouble(0xFFF8555555555555L), NaNd}, 64 {Double.longBitsToDouble(0x7FFFFFFFFFFFFFFFL), NaNd}, 65 {Double.longBitsToDouble(0xFFFFFFFFFFFFFFFFL), NaNd}, 66 {Double.longBitsToDouble(0x7FFDeadBeef00000L), NaNd}, 67 {Double.longBitsToDouble(0xFFFDeadBeef00000L), NaNd}, 68 {Double.longBitsToDouble(0x7FFCafeBabe00000L), NaNd}, 69 {Double.longBitsToDouble(0xFFFCafeBabe00000L), NaNd}, 70 {Double.NEGATIVE_INFINITY, NaNd}, 71 {-8.0, NaNd}, 72 {-1.0, NaNd}, 73 {-DoubleConsts.MIN_NORMAL, NaNd}, 74 {-Double.MIN_VALUE, NaNd}, 75 {-0.0, -infinityD}, 76 {+0.0, -infinityD}, 77 {+1.0, 0.0}, 78 {Double.POSITIVE_INFINITY, infinityD}, 79 }; 80 81 // Test special cases 82 for(int i = 0; i < testCases.length; i++) { 83 failures += testLog10Case(testCases[i][0], 84 testCases[i][1]); 85 } 86 87 // Test log10(10^n) == n for integer n; 10^n, n < 0 is not 88 // exactly representable as a floating-point value -- up to 89 // 10^22 can be represented exactly 90 double testCase = 1.0; 91 for(int i = 0; i < 23; i++) { 92 failures += testLog10Case(testCase, i); 93 testCase *= 10.0; 94 } 95 96 // Test for gross inaccuracy by comparing to log; should be 97 // within a few ulps of log(x)/log(10) 98 for(int i = 0; i < 10000; i++) { 99 double input = Double.longBitsToDouble(rand.nextLong()); 100 if(! Double.isFinite(input)) 101 continue; // avoid testing NaN and infinite values 102 else { 103 input = Math.abs(input); 104 105 double expected = StrictMath.log(input)/LN_10; 106 if( ! Double.isFinite(expected)) 107 continue; // if log(input) overflowed, try again 108 else { 109 double result; 110 111 if( Math.abs(((result=Math.log10(input)) - expected)/Math.ulp(expected)) > 3) { 112 failures++; 113 System.err.println("For input " + input + 114 ", Math.log10 was more than 3 ulps different from " + 115 "log(input)/log(10): log10(input) = " + result + 116 "\tlog(input)/log(10) = " + expected); 117 } 118 119 if( Math.abs(((result=StrictMath.log10(input)) - expected)/Math.ulp(expected)) > 3) { 120 failures++; 121 System.err.println("For input " + input + 122 ", StrictMath.log10 was more than 3 ulps different from " + 123 "log(input)/log(10): log10(input) = " + result + 124 "\tlog(input)/log(10) = " + expected); 125 } 126 127 128 } 129 } 130 } 131 132 // Test for accuracy and monotonicity near log10(1.0). From 133 // the Taylor expansion of log, 134 // log10(1+z) ~= (z -(z^2)/2)/LN_10; 135 { 136 double neighbors[] = new double[40]; 137 double neighborsStrict[] = new double[40]; 138 double z = Double.NaN; 139 140 // Test inputs greater than 1.0. 141 neighbors[0] = Math.log10(1.0); 142 neighborsStrict[0] = StrictMath.log10(1.0); 143 144 double input[] = new double[40]; 145 int half = input.length/2; 146 147 148 // Initialize input to the 40 consecutive double values 149 // "centered" at 1.0. 150 double up = Double.NaN; 151 double down = Double.NaN; 152 for(int i = 0; i < half; i++) { 153 if (i == 0) { 154 input[half] = 1.0; 155 up = Math.nextUp(1.0); 156 down = Math.nextDown(1.0); 157 } else { 158 input[half + i] = up; 159 input[half - i] = down; 160 up = Math.nextUp(up); 161 down = Math.nextDown(down); 162 } 163 } 164 input[0] = Math.nextDown(input[1]); 165 166 for(int i = 0; i < neighbors.length; i++) { 167 neighbors[i] = Math.log10(input[i]); 168 neighborsStrict[i] = StrictMath.log10(input[i]); 169 170 // Test accuracy. 171 z = input[i] - 1.0; 172 double expected = (z - (z*z)*0.5)/LN_10; 173 if ( Math.abs(neighbors[i] - expected ) > 3*Math.ulp(expected) ) { 174 failures++; 175 System.err.println("For input near 1.0 " + input[i] + 176 ", Math.log10(1+z) was more than 3 ulps different from " + 177 "(z-(z^2)/2)/ln(10): log10(input) = " + neighbors[i] + 178 "\texpected about = " + expected); 179 } 180 181 if ( Math.abs(neighborsStrict[i] - expected ) > 3*Math.ulp(expected) ) { 182 failures++; 183 System.err.println("For input near 1.0 " + input[i] + 184 ", StrictMath.log10(1+z) was more than 3 ulps different from " + 185 "(z-(z^2)/2)/ln(10): log10(input) = " + neighborsStrict[i] + 186 "\texpected about = " + expected); 187 } 188 189 // Test monotonicity 190 if( i > 0) { 191 if( neighbors[i-1] > neighbors[i] ) { 192 failures++; 193 System.err.println("Monotonicity failure for Math.log10 at " + input[i] + 194 " and prior value."); 195 } 196 197 if( neighborsStrict[i-1] > neighborsStrict[i] ) { 198 failures++; 199 System.err.println("Monotonicity failure for StrictMath.log10 at " + input[i] + 200 " and prior value."); 201 } 202 } 203 } 204 205 } 206 207 return failures; 208 } 209 210 public static void main(String argv[]) { 211 int failures = 0; 212 213 failures += testLog10(); 214 215 if (failures > 0) { 216 System.err.println("Testing log10 incurred " 217 + failures + " failures."); 218 throw new RuntimeException(); 219 } 220 } 221 222 }