/* * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved. * 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. * * 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. */ /* * @test * @bug 4074599 4939441 * @summary Tests for {Math, StrictMath}.log10 * @author Joseph D. Darcy */ package test.java.lang.Math; import org.testng.annotations.Test; import org.testng.Assert; 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 void testLog10Case(double input, double expected) { Tests.test("Math.log10(double)", input, Math.log10(input), expected); Tests.test("StrictMath.log10(double)", input, StrictMath.log10(input), expected); } @Test public void testLog10() { 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}, {-Double.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 (double[] aCase : testCases) { testLog10Case(aCase[0], aCase[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++) { 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()); if (!Double.isFinite(input)) { continue; // avoid testing NaN and infinite values } else { input = Math.abs(input); double expected = StrictMath.log(input) / LN_10; if (!Double.isFinite(expected)) { continue; // if log(input) overflowed, try again } else { double result; if (Math.abs(((result = Math.log10(input)) - expected) / Math.ulp(expected)) > 3) { Assert.fail("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) { Assert.fail("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; up = Math.nextUp(1.0); down = Math.nextDown(1.0); } else { input[half + i] = up; input[half - i] = down; up = Math.nextUp(up); down = Math.nextDown(down); } } input[0] = Math.nextDown(input[1]); 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)) { Assert.fail("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)) { Assert.fail("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]) { Assert.fail("Monotonicity failure for Math.log10 at " + input[i] + " and prior value."); } if (neighborsStrict[i - 1] > neighborsStrict[i]) { Assert.fail("Monotonicity failure for StrictMath.log10 at " + input[i] + " and prior value."); } } } } } }