212 lines
8.1 KiB
Java
212 lines
8.1 KiB
Java
/*
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* Copyright (c) 2003, 2023, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* @test
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* @bug 4074599 4939441
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* @build Tests
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* @build Log10Tests
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* @run main Log10Tests
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* @summary Tests for {Math, StrictMath}.log10
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*/
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import static java.lang.Double.longBitsToDouble;
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public class Log10Tests {
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private Log10Tests(){}
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private static final double infinityD = Double.POSITIVE_INFINITY;
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private static final double NaNd = Double.NaN;
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private static final double LN_10 = StrictMath.log(10.0);
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// Initialize shared random number generator
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static java.util.Random rand = new java.util.Random(0L);
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private static int testLog10Case(double input, double expected) {
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int failures=0;
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failures += Tests.test("Math.log10", input, Math::log10, expected);
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failures += Tests.test("StrictMath.log10", input, StrictMath::log10, expected);
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return failures;
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}
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private static int testLog10() {
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int failures = 0;
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for(double nan : Tests.NaNs) {
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failures += testLog10Case(nan, NaNd);
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}
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double [][] testCases = {
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{Double.NEGATIVE_INFINITY, NaNd},
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{-8.0, NaNd},
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{-1.0, NaNd},
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{-Double.MIN_NORMAL, NaNd},
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{-Double.MIN_VALUE, NaNd},
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{-0.0, -infinityD},
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{+0.0, -infinityD},
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{+1.0, 0.0},
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{Double.POSITIVE_INFINITY, infinityD},
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};
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// Test special cases
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for(int i = 0; i < testCases.length; i++) {
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failures += testLog10Case(testCases[i][0],
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testCases[i][1]);
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}
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// Test log10(10^n) == n for integer n; 10^n, n < 0 is not
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// exactly representable as a floating-point value -- up to
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// 10^22 can be represented exactly
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double testCase = 1.0;
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for(int i = 0; i < 23; i++) {
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failures += testLog10Case(testCase, i);
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testCase *= 10.0;
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}
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// Test for gross inaccuracy by comparing to log; should be
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// within a few ulps of log(x)/log(10)
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for(int i = 0; i < 10000; i++) {
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double input = Double.longBitsToDouble(rand.nextLong());
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if(! Double.isFinite(input))
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continue; // avoid testing NaN and infinite values
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else {
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input = Math.abs(input);
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double expected = StrictMath.log(input)/LN_10;
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if( ! Double.isFinite(expected))
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continue; // if log(input) overflowed, try again
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else {
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double result;
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if( Math.abs(((result=Math.log10(input)) - expected)/Math.ulp(expected)) > 3) {
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failures++;
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System.err.println("For input " + input +
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", Math.log10 was more than 3 ulps different from " +
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"log(input)/log(10): log10(input) = " + result +
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"\tlog(input)/log(10) = " + expected);
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}
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if( Math.abs(((result=StrictMath.log10(input)) - expected)/Math.ulp(expected)) > 3) {
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failures++;
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System.err.println("For input " + input +
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", StrictMath.log10 was more than 3 ulps different from " +
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"log(input)/log(10): log10(input) = " + result +
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"\tlog(input)/log(10) = " + expected);
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}
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}
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}
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}
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// Test for accuracy and monotonicity near log10(1.0). From
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// the Taylor expansion of log,
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// log10(1+z) ~= (z -(z^2)/2)/LN_10;
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{
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double neighbors[] = new double[40];
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double neighborsStrict[] = new double[40];
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double z = Double.NaN;
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// Test inputs greater than 1.0.
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neighbors[0] = Math.log10(1.0);
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neighborsStrict[0] = StrictMath.log10(1.0);
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double input[] = new double[40];
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int half = input.length/2;
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// Initialize input to the 40 consecutive double values
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// "centered" at 1.0.
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double up = Double.NaN;
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double down = Double.NaN;
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for(int i = 0; i < half; i++) {
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if (i == 0) {
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input[half] = 1.0;
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up = Math.nextUp(1.0);
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down = Math.nextDown(1.0);
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} else {
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input[half + i] = up;
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input[half - i] = down;
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up = Math.nextUp(up);
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down = Math.nextDown(down);
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}
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}
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input[0] = Math.nextDown(input[1]);
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for(int i = 0; i < neighbors.length; i++) {
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neighbors[i] = Math.log10(input[i]);
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neighborsStrict[i] = StrictMath.log10(input[i]);
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// Test accuracy.
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z = input[i] - 1.0;
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double expected = (z - (z*z)*0.5)/LN_10;
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if ( Math.abs(neighbors[i] - expected ) > 3*Math.ulp(expected) ) {
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failures++;
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System.err.println("For input near 1.0 " + input[i] +
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", Math.log10(1+z) was more than 3 ulps different from " +
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"(z-(z^2)/2)/ln(10): log10(input) = " + neighbors[i] +
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"\texpected about = " + expected);
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}
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if ( Math.abs(neighborsStrict[i] - expected ) > 3*Math.ulp(expected) ) {
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failures++;
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System.err.println("For input near 1.0 " + input[i] +
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", StrictMath.log10(1+z) was more than 3 ulps different from " +
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"(z-(z^2)/2)/ln(10): log10(input) = " + neighborsStrict[i] +
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"\texpected about = " + expected);
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}
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// Test monotonicity
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if( i > 0) {
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if( neighbors[i-1] > neighbors[i] ) {
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failures++;
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System.err.println("Monotonicity failure for Math.log10 at " + input[i] +
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" and prior value.");
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}
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if( neighborsStrict[i-1] > neighborsStrict[i] ) {
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failures++;
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System.err.println("Monotonicity failure for StrictMath.log10 at " + input[i] +
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" and prior value.");
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}
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}
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}
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}
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return failures;
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}
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public static void main(String... argv) {
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int failures = 0;
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failures += testLog10();
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if (failures > 0) {
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System.err.println("Testing log10 incurred "
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+ failures + " failures.");
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throw new RuntimeException();
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}
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}
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}
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