Log10Tests.java 8.8 KB
Newer Older
1
/*
2
 * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
19 20 21
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
 */

/*
 * @test
 * @bug 4074599 4939441
 * @summary Tests for {Math, StrictMath}.log10
 * @author Joseph D. Darcy
 */

import sun.misc.DoubleConsts;

public class Log10Tests {
    private Log10Tests(){}

    static final double infinityD = Double.POSITIVE_INFINITY;
    static final double NaNd = Double.NaN;
    static final double LN_10 = StrictMath.log(10.0);

    // Initialize shared random number generator
    static java.util.Random rand = new java.util.Random(0L);

    static int testLog10Case(double input, double expected) {
        int failures=0;

        failures+=Tests.test("Math.log10(double)", input,
                             Math.log10(input), expected);

        failures+=Tests.test("StrictMath.log10(double)", input,
                             StrictMath.log10(input), expected);

        return failures;
    }

    static int testLog10() {
        int failures = 0;

        double [][] testCases = {
            {Double.NaN,                NaNd},
            {Double.longBitsToDouble(0x7FF0000000000001L),      NaNd},
            {Double.longBitsToDouble(0xFFF0000000000001L),      NaNd},
            {Double.longBitsToDouble(0x7FF8555555555555L),      NaNd},
            {Double.longBitsToDouble(0xFFF8555555555555L),      NaNd},
            {Double.longBitsToDouble(0x7FFFFFFFFFFFFFFFL),      NaNd},
            {Double.longBitsToDouble(0xFFFFFFFFFFFFFFFFL),      NaNd},
            {Double.longBitsToDouble(0x7FFDeadBeef00000L),      NaNd},
            {Double.longBitsToDouble(0xFFFDeadBeef00000L),      NaNd},
            {Double.longBitsToDouble(0x7FFCafeBabe00000L),      NaNd},
            {Double.longBitsToDouble(0xFFFCafeBabe00000L),      NaNd},
            {Double.NEGATIVE_INFINITY,  NaNd},
            {-8.0,                      NaNd},
            {-1.0,                      NaNd},
            {-DoubleConsts.MIN_NORMAL,  NaNd},
            {-Double.MIN_VALUE,         NaNd},
            {-0.0,                      -infinityD},
            {+0.0,                      -infinityD},
            {+1.0,                      0.0},
            {Double.POSITIVE_INFINITY,  infinityD},
        };

        // Test special cases
        for(int i = 0; i < testCases.length; i++) {
            failures += testLog10Case(testCases[i][0],
                                          testCases[i][1]);
        }

        // Test log10(10^n) == n for integer n; 10^n, n < 0 is not
        // exactly representable as a floating-point value -- up to
        // 10^22 can be represented exactly
        double testCase = 1.0;
        for(int i = 0; i < 23; i++) {
            failures += testLog10Case(testCase, i);
            testCase *= 10.0;
        }

        // Test for gross inaccuracy by comparing to log; should be
        // within a few ulps of log(x)/log(10)
        for(int i = 0; i < 10000; i++) {
            double input = Double.longBitsToDouble(rand.nextLong());
100
            if(! Double.isFinite(input))
101 102 103 104 105
                continue; // avoid testing NaN and infinite values
            else {
                input = Math.abs(input);

                double expected = StrictMath.log(input)/LN_10;
106
                if( ! Double.isFinite(expected))
107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154
                    continue; // if log(input) overflowed, try again
                else {
                    double result;

                    if( Math.abs(((result=Math.log10(input)) - expected)/Math.ulp(expected)) > 3) {
                        failures++;
                        System.err.println("For input " + input +
                                           ", Math.log10 was more than 3 ulps different from " +
                                           "log(input)/log(10): log10(input) = " + result +
                                           "\tlog(input)/log(10) = " + expected);
                    }

                    if( Math.abs(((result=StrictMath.log10(input)) - expected)/Math.ulp(expected)) > 3) {
                        failures++;
                        System.err.println("For input " + input +
                                           ", StrictMath.log10 was more than 3 ulps different from " +
                                           "log(input)/log(10): log10(input) = " + result +
                                           "\tlog(input)/log(10) = " + expected);
                    }


                }
            }
        }

        // Test for accuracy and monotonicity near log10(1.0).  From
        // the Taylor expansion of log,
        // log10(1+z) ~= (z -(z^2)/2)/LN_10;
        {
            double neighbors[] =        new double[40];
            double neighborsStrict[] =  new double[40];
            double z = Double.NaN;

            // Test inputs greater than 1.0.
            neighbors[0] =              Math.log10(1.0);
            neighborsStrict[0] =        StrictMath.log10(1.0);

            double input[] =  new double[40];
            int half = input.length/2;


            // Initialize input to the 40 consecutive double values
            // "centered" at 1.0.
            double up = Double.NaN;
            double down = Double.NaN;
            for(int i = 0; i < half; i++) {
                if (i == 0) {
                    input[half] = 1.0;
155
                    up   = Math.nextUp(1.0);
156
                    down = Math.nextDown(1.0);
157 158 159
                } else {
                    input[half + i] = up;
                    input[half - i] = down;
160
                    up   = Math.nextUp(up);
161
                    down = Math.nextDown(down);
162 163
                }
            }
164
            input[0] = Math.nextDown(input[1]);
165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222

            for(int i = 0; i < neighbors.length; i++) {
                neighbors[i] =          Math.log10(input[i]);
                neighborsStrict[i] =    StrictMath.log10(input[i]);

                // Test accuracy.
                z = input[i] - 1.0;
                double expected = (z - (z*z)*0.5)/LN_10;
                if ( Math.abs(neighbors[i] - expected ) > 3*Math.ulp(expected) ) {
                    failures++;
                    System.err.println("For input near 1.0 " + input[i] +
                                       ", Math.log10(1+z) was more than 3 ulps different from " +
                                       "(z-(z^2)/2)/ln(10): log10(input) = " + neighbors[i] +
                                       "\texpected about = " + expected);
                }

                if ( Math.abs(neighborsStrict[i] - expected ) > 3*Math.ulp(expected) ) {
                    failures++;
                    System.err.println("For input near 1.0 " + input[i] +
                                       ", StrictMath.log10(1+z) was more than 3 ulps different from " +
                                       "(z-(z^2)/2)/ln(10): log10(input) = " + neighborsStrict[i] +
                                       "\texpected about = " + expected);
                }

                // Test monotonicity
                if( i > 0) {
                    if( neighbors[i-1] > neighbors[i] ) {
                        failures++;
                        System.err.println("Monotonicity failure for Math.log10  at " + input[i] +
                                           " and prior value.");
                    }

                    if( neighborsStrict[i-1] > neighborsStrict[i] ) {
                        failures++;
                        System.err.println("Monotonicity failure for StrictMath.log10  at " + input[i] +
                                           " and prior value.");
                    }
                }
            }

        }

        return failures;
    }

    public static void main(String argv[]) {
        int failures = 0;

        failures += testLog10();

        if (failures > 0) {
            System.err.println("Testing log10 incurred "
                               + failures + " failures.");
            throw new RuntimeException();
        }
    }

}