diff -r 9ac11db6b69b -r 39d505a353e8 jdk/test/java/lang/Math/Log1pTests.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/jdk/test/java/lang/Math/Log1pTests.java Mon Jan 26 19:49:26 2009 -0800 @@ -0,0 +1,206 @@ +/* + * Copyright 2003 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + */ + +/* + * @test + * @bug 4851638 4939441 + * @summary Tests for {Math, StrictMath}.log1p + * @author Joseph D. Darcy + */ + +import sun.misc.DoubleConsts; +import sun.misc.FpUtils; + +public class Log1pTests { + private Log1pTests(){} + + static final double infinityD = Double.POSITIVE_INFINITY; + static final double NaNd = Double.NaN; + + /** + * Formulation taken from HP-15C Advanced Functions Handbook, part + * number HP 0015-90011, p 181. This is accurate to a few ulps. + */ + static double hp15cLogp(double x) { + double u = 1.0 + x; + return (u==1.0? x : StrictMath.log(u)*x/(u-1) ); + } + + /* + * The Taylor expansion of ln(1 + x) for -1 < x <= 1 is: + * + * x - x^2/2 + x^3/3 - ... -(-x^j)/j + * + * Therefore, for small values of x, log1p(x) ~= x. For large + * values of x, log1p(x) ~= log(x). + * + * Also x/(x+1) < ln(1+x) < x + */ + + static int testLog1p() { + 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, -infinityD}, + {-0.0, -0.0}, + {+0.0, +0.0}, + {infinityD, infinityD}, + }; + + // Test special cases + for(int i = 0; i < testCases.length; i++) { + failures += testLog1pCaseWithUlpDiff(testCases[i][0], + testCases[i][1], 0); + } + + // For |x| < 2^-54 log1p(x) ~= x + for(int i = DoubleConsts.MIN_SUB_EXPONENT; i <= -54; i++) { + double d = FpUtils.scalb(2, i); + failures += testLog1pCase(d, d); + failures += testLog1pCase(-d, -d); + } + + // For x > 2^53 log1p(x) ~= log(x) + for(int i = 53; i <= DoubleConsts.MAX_EXPONENT; i++) { + double d = FpUtils.scalb(2, i); + failures += testLog1pCaseWithUlpDiff(d, StrictMath.log(d), 2.001); + } + + // Construct random values with exponents ranging from -53 to + // 52 and compare against HP-15C formula. + java.util.Random rand = new java.util.Random(); + for(int i = 0; i < 1000; i++) { + double d = rand.nextDouble(); + + d = FpUtils.scalb(d, -53 - FpUtils.ilogb(d)); + + for(int j = -53; j <= 52; j++) { + failures += testLog1pCaseWithUlpDiff(d, hp15cLogp(d), 5); + + d *= 2.0; // increase exponent by 1 + } + } + + // Test for monotonicity failures near values y-1 where y ~= + // e^x. Test two numbers before and two numbers after each + // chosen value; i.e. + // + // pcNeighbors[] = + // {nextDown(nextDown(pc)), + // nextDown(pc), + // pc, + // nextUp(pc), + // nextUp(nextUp(pc))} + // + // and we test that log1p(pcNeighbors[i]) <= log1p(pcNeighbors[i+1]) + { + double pcNeighbors[] = new double[5]; + double pcNeighborsLog1p[] = new double[5]; + double pcNeighborsStrictLog1p[] = new double[5]; + + for(int i = -36; i <= 36; i++) { + double pc = StrictMath.pow(Math.E, i) - 1; + + pcNeighbors[2] = pc; + pcNeighbors[1] = FpUtils.nextDown(pc); + pcNeighbors[0] = FpUtils.nextDown(pcNeighbors[1]); + pcNeighbors[3] = FpUtils.nextUp(pc); + pcNeighbors[4] = FpUtils.nextUp(pcNeighbors[3]); + + for(int j = 0; j < pcNeighbors.length; j++) { + pcNeighborsLog1p[j] = Math.log1p(pcNeighbors[j]); + pcNeighborsStrictLog1p[j] = StrictMath.log1p(pcNeighbors[j]); + } + + for(int j = 0; j < pcNeighborsLog1p.length-1; j++) { + if(pcNeighborsLog1p[j] > pcNeighborsLog1p[j+1] ) { + failures++; + System.err.println("Monotonicity failure for Math.log1p on " + + pcNeighbors[j] + " and " + + pcNeighbors[j+1] + "\n\treturned " + + pcNeighborsLog1p[j] + " and " + + pcNeighborsLog1p[j+1] ); + } + + if(pcNeighborsStrictLog1p[j] > pcNeighborsStrictLog1p[j+1] ) { + failures++; + System.err.println("Monotonicity failure for StrictMath.log1p on " + + pcNeighbors[j] + " and " + + pcNeighbors[j+1] + "\n\treturned " + + pcNeighborsStrictLog1p[j] + " and " + + pcNeighborsStrictLog1p[j+1] ); + } + + + } + + } + } + + return failures; + } + + public static int testLog1pCase(double input, + double expected) { + return testLog1pCaseWithUlpDiff(input, expected, 1); + } + + public static int testLog1pCaseWithUlpDiff(double input, + double expected, + double ulps) { + int failures = 0; + failures += Tests.testUlpDiff("Math.lop1p(double", + input, Math.log1p(input), + expected, ulps); + failures += Tests.testUlpDiff("StrictMath.log1p(double", + input, StrictMath.log1p(input), + expected, ulps); + return failures; + } + + public static void main(String argv[]) { + int failures = 0; + + failures += testLog1p(); + + if (failures > 0) { + System.err.println("Testing log1p incurred " + + failures + " failures."); + throw new RuntimeException(); + } + } + +}