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 * @library /lib/testlibrary 29 * @build jdk.testlibrary.DoubleUtils jdk.testlibrary.FloatUtils 30 * @run main Log10Tests 31 * @author Joseph D. Darcy 32 */ 33 34 public class Log10Tests { 35 private Log10Tests(){} 36 37 static final double infinityD = Double.POSITIVE_INFINITY; 38 static final double NaNd = Double.NaN; 39 static final double LN_10 = StrictMath.log(10.0); 40 41 // Initialize shared random number generator 42 static java.util.Random rand = new java.util.Random(0L); 43 44 static int testLog10Case(double input, double expected) { 45 int failures=0; 46 47 failures+=Tests.test("Math.log10(double)", input, 48 Math.log10(input), expected); 49 50 failures+=Tests.test("StrictMath.log10(double)", input, 51 StrictMath.log10(input), expected); 52 53 return failures; 54 } 55 56 static int testLog10() { 57 int failures = 0; 58 59 double [][] testCases = { 60 {Double.NaN, NaNd}, 61 {Double.longBitsToDouble(0x7FF0000000000001L), NaNd}, 62 {Double.longBitsToDouble(0xFFF0000000000001L), NaNd}, 63 {Double.longBitsToDouble(0x7FF8555555555555L), NaNd}, 64 {Double.longBitsToDouble(0xFFF8555555555555L), NaNd}, 65 {Double.longBitsToDouble(0x7FFFFFFFFFFFFFFFL), NaNd}, 66 {Double.longBitsToDouble(0xFFFFFFFFFFFFFFFFL), NaNd}, 67 {Double.longBitsToDouble(0x7FFDeadBeef00000L), NaNd}, 68 {Double.longBitsToDouble(0xFFFDeadBeef00000L), NaNd}, 69 {Double.longBitsToDouble(0x7FFCafeBabe00000L), NaNd}, 70 {Double.longBitsToDouble(0xFFFCafeBabe00000L), NaNd}, 71 {Double.NEGATIVE_INFINITY, NaNd}, 72 {-8.0, NaNd}, 73 {-1.0, NaNd}, 74 {-Double.MIN_NORMAL, NaNd}, 75 {-Double.MIN_VALUE, NaNd}, 76 {-0.0, -infinityD}, 77 {+0.0, -infinityD}, 78 {+1.0, 0.0}, 79 {Double.POSITIVE_INFINITY, infinityD}, 80 }; 81 82 // Test special cases 83 for(int i = 0; i < testCases.length; i++) { 84 failures += testLog10Case(testCases[i][0], 85 testCases[i][1]); 86 } 87 88 // Test log10(10^n) == n for integer n; 10^n, n < 0 is not 89 // exactly representable as a floating-point value -- up to 90 // 10^22 can be represented exactly 91 double testCase = 1.0; 92 for(int i = 0; i < 23; i++) { 93 failures += testLog10Case(testCase, i); 94 testCase *= 10.0; 95 } 96 97 // Test for gross inaccuracy by comparing to log; should be 98 // within a few ulps of log(x)/log(10) 99 for(int i = 0; i < 10000; i++) { 100 double input = Double.longBitsToDouble(rand.nextLong()); 101 if(! Double.isFinite(input)) 102 continue; // avoid testing NaN and infinite values 103 else { 104 input = Math.abs(input); 105 106 double expected = StrictMath.log(input)/LN_10; 107 if( ! Double.isFinite(expected)) 108 continue; // if log(input) overflowed, try again 109 else { 110 double result; 111 112 if( Math.abs(((result=Math.log10(input)) - expected)/Math.ulp(expected)) > 3) { 113 failures++; 114 System.err.println("For input " + input + 115 ", Math.log10 was more than 3 ulps different from " + 116 "log(input)/log(10): log10(input) = " + result + 117 "\tlog(input)/log(10) = " + expected); 118 } 119 120 if( Math.abs(((result=StrictMath.log10(input)) - expected)/Math.ulp(expected)) > 3) { 121 failures++; 122 System.err.println("For input " + input + 123 ", StrictMath.log10 was more than 3 ulps different from " + 124 "log(input)/log(10): log10(input) = " + result + 125 "\tlog(input)/log(10) = " + expected); 126 } 127 128 129 } 130 } 131 } 132 133 // Test for accuracy and monotonicity near log10(1.0). From 134 // the Taylor expansion of log, 135 // log10(1+z) ~= (z -(z^2)/2)/LN_10; 136 { 137 double neighbors[] = new double[40]; 138 double neighborsStrict[] = new double[40]; 139 double z = Double.NaN; 140 141 // Test inputs greater than 1.0. 142 neighbors[0] = Math.log10(1.0); 143 neighborsStrict[0] = StrictMath.log10(1.0); 144 145 double input[] = new double[40]; 146 int half = input.length/2; 147 148 149 // Initialize input to the 40 consecutive double values 150 // "centered" at 1.0. 151 double up = Double.NaN; 152 double down = Double.NaN; 153 for(int i = 0; i < half; i++) { 154 if (i == 0) { 155 input[half] = 1.0; 156 up = Math.nextUp(1.0); 157 down = Math.nextDown(1.0); 158 } else { 159 input[half + i] = up; 160 input[half - i] = down; 161 up = Math.nextUp(up); 162 down = Math.nextDown(down); 163 } 164 } 165 input[0] = Math.nextDown(input[1]); 166 167 for(int i = 0; i < neighbors.length; i++) { 168 neighbors[i] = Math.log10(input[i]); 169 neighborsStrict[i] = StrictMath.log10(input[i]); 170 171 // Test accuracy. 172 z = input[i] - 1.0; 173 double expected = (z - (z*z)*0.5)/LN_10; 174 if ( Math.abs(neighbors[i] - expected ) > 3*Math.ulp(expected) ) { 175 failures++; 176 System.err.println("For input near 1.0 " + input[i] + 177 ", Math.log10(1+z) was more than 3 ulps different from " + 178 "(z-(z^2)/2)/ln(10): log10(input) = " + neighbors[i] + 179 "\texpected about = " + expected); 180 } 181 182 if ( Math.abs(neighborsStrict[i] - expected ) > 3*Math.ulp(expected) ) { 183 failures++; 184 System.err.println("For input near 1.0 " + input[i] + 185 ", StrictMath.log10(1+z) was more than 3 ulps different from " + 186 "(z-(z^2)/2)/ln(10): log10(input) = " + neighborsStrict[i] + 187 "\texpected about = " + expected); 188 } 189 190 // Test monotonicity 191 if( i > 0) { 192 if( neighbors[i-1] > neighbors[i] ) { 193 failures++; 194 System.err.println("Monotonicity failure for Math.log10 at " + input[i] + 195 " and prior value."); 196 } 197 198 if( neighborsStrict[i-1] > neighborsStrict[i] ) { 199 failures++; 200 System.err.println("Monotonicity failure for StrictMath.log10 at " + input[i] + 201 " and prior value."); 202 } 203 } 204 } 205 206 } 207 208 return failures; 209 } 210 211 public static void main(String argv[]) { 212 int failures = 0; 213 214 failures += testLog10(); 215 216 if (failures > 0) { 217 System.err.println("Testing log10 incurred " 218 + failures + " failures."); 219 throw new RuntimeException(); 220 } 221 } 222 223 }