author | jrose |
Sat, 05 Oct 2013 05:30:38 -0700 | |
changeset 20528 | 0b1e2130d3f7 |
parent 14856 | 92a1bcf46888 |
child 22634 | 9c18aebe9229 |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 2003, 2011, 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 4851638 4939441 |
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* @summary Tests for {Math, StrictMath}.log1p |
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* @author Joseph D. Darcy |
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*/ |
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import sun.misc.DoubleConsts; |
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import sun.misc.FpUtils; |
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public class Log1pTests { |
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private Log1pTests(){} |
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static final double infinityD = Double.POSITIVE_INFINITY; |
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static final double NaNd = Double.NaN; |
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/** |
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* Formulation taken from HP-15C Advanced Functions Handbook, part |
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* number HP 0015-90011, p 181. This is accurate to a few ulps. |
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*/ |
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static double hp15cLogp(double x) { |
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double u = 1.0 + x; |
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return (u==1.0? x : StrictMath.log(u)*x/(u-1) ); |
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} |
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/* |
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* The Taylor expansion of ln(1 + x) for -1 < x <= 1 is: |
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* |
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* x - x^2/2 + x^3/3 - ... -(-x^j)/j |
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* |
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* Therefore, for small values of x, log1p(x) ~= x. For large |
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* values of x, log1p(x) ~= log(x). |
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* |
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* Also x/(x+1) < ln(1+x) < x |
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*/ |
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static int testLog1p() { |
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int failures = 0; |
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double [][] testCases = { |
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{Double.NaN, NaNd}, |
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{Double.longBitsToDouble(0x7FF0000000000001L), NaNd}, |
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{Double.longBitsToDouble(0xFFF0000000000001L), NaNd}, |
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{Double.longBitsToDouble(0x7FF8555555555555L), NaNd}, |
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{Double.longBitsToDouble(0xFFF8555555555555L), NaNd}, |
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{Double.longBitsToDouble(0x7FFFFFFFFFFFFFFFL), NaNd}, |
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{Double.longBitsToDouble(0xFFFFFFFFFFFFFFFFL), NaNd}, |
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{Double.longBitsToDouble(0x7FFDeadBeef00000L), NaNd}, |
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{Double.longBitsToDouble(0xFFFDeadBeef00000L), NaNd}, |
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{Double.longBitsToDouble(0x7FFCafeBabe00000L), NaNd}, |
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{Double.longBitsToDouble(0xFFFCafeBabe00000L), NaNd}, |
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{Double.NEGATIVE_INFINITY, NaNd}, |
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{-8.0, NaNd}, |
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{-1.0, -infinityD}, |
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{-0.0, -0.0}, |
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{+0.0, +0.0}, |
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{infinityD, 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 += testLog1pCaseWithUlpDiff(testCases[i][0], |
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testCases[i][1], 0); |
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} |
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// For |x| < 2^-54 log1p(x) ~= x |
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for(int i = DoubleConsts.MIN_SUB_EXPONENT; i <= -54; i++) { |
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darcy
parents:
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double d = Math.scalb(2, i); |
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failures += testLog1pCase(d, d); |
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failures += testLog1pCase(-d, -d); |
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} |
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// For x > 2^53 log1p(x) ~= log(x) |
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for(int i = 53; i <= DoubleConsts.MAX_EXPONENT; i++) { |
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double d = Math.scalb(2, i); |
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failures += testLog1pCaseWithUlpDiff(d, StrictMath.log(d), 2.001); |
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} |
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// Construct random values with exponents ranging from -53 to |
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// 52 and compare against HP-15C formula. |
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java.util.Random rand = new java.util.Random(); |
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for(int i = 0; i < 1000; i++) { |
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double d = rand.nextDouble(); |
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d = Math.scalb(d, -53 - FpUtils.ilogb(d)); |
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for(int j = -53; j <= 52; j++) { |
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failures += testLog1pCaseWithUlpDiff(d, hp15cLogp(d), 5); |
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d *= 2.0; // increase exponent by 1 |
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} |
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} |
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// Test for monotonicity failures near values y-1 where y ~= |
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// e^x. Test two numbers before and two numbers after each |
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// chosen value; i.e. |
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// |
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// pcNeighbors[] = |
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// {nextDown(nextDown(pc)), |
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// nextDown(pc), |
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// pc, |
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// nextUp(pc), |
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// nextUp(nextUp(pc))} |
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// |
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// and we test that log1p(pcNeighbors[i]) <= log1p(pcNeighbors[i+1]) |
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{ |
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double pcNeighbors[] = new double[5]; |
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double pcNeighborsLog1p[] = new double[5]; |
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double pcNeighborsStrictLog1p[] = new double[5]; |
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for(int i = -36; i <= 36; i++) { |
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double pc = StrictMath.pow(Math.E, i) - 1; |
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pcNeighbors[2] = pc; |
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pcNeighbors[1] = Math.nextDown(pc); |
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pcNeighbors[0] = Math.nextDown(pcNeighbors[1]); |
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pcNeighbors[3] = Math.nextUp(pc); |
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pcNeighbors[4] = Math.nextUp(pcNeighbors[3]); |
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for(int j = 0; j < pcNeighbors.length; j++) { |
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pcNeighborsLog1p[j] = Math.log1p(pcNeighbors[j]); |
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pcNeighborsStrictLog1p[j] = StrictMath.log1p(pcNeighbors[j]); |
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} |
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for(int j = 0; j < pcNeighborsLog1p.length-1; j++) { |
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if(pcNeighborsLog1p[j] > pcNeighborsLog1p[j+1] ) { |
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failures++; |
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System.err.println("Monotonicity failure for Math.log1p on " + |
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pcNeighbors[j] + " and " + |
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pcNeighbors[j+1] + "\n\treturned " + |
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pcNeighborsLog1p[j] + " and " + |
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pcNeighborsLog1p[j+1] ); |
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} |
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if(pcNeighborsStrictLog1p[j] > pcNeighborsStrictLog1p[j+1] ) { |
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failures++; |
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System.err.println("Monotonicity failure for StrictMath.log1p on " + |
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pcNeighbors[j] + " and " + |
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pcNeighbors[j+1] + "\n\treturned " + |
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pcNeighborsStrictLog1p[j] + " and " + |
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pcNeighborsStrictLog1p[j+1] ); |
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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 int testLog1pCase(double input, |
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double expected) { |
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return testLog1pCaseWithUlpDiff(input, expected, 1); |
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} |
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public static int testLog1pCaseWithUlpDiff(double input, |
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double expected, |
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double ulps) { |
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int failures = 0; |
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failures += Tests.testUlpDiff("Math.lop1p(double", |
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input, Math.log1p(input), |
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expected, ulps); |
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failures += Tests.testUlpDiff("StrictMath.log1p(double", |
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input, StrictMath.log1p(input), |
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expected, ulps); |
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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 += testLog1p(); |
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if (failures > 0) { |
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System.err.println("Testing log1p 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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} |