| /* |
| * Copyright (c) 2003, 2017, 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 |
| * @library /test/lib |
| * @build jdk.test.lib.RandomFactory |
| * @run main Log1pTests |
| * @bug 4851638 4939441 8078672 |
| * @summary Tests for {Math, StrictMath}.log1p (use -Dseed=X to set PRNG seed) |
| * @author Joseph D. Darcy |
| * @key randomness |
| */ |
| |
| import jdk.test.lib.RandomFactory; |
| |
| 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 = Math.scalb(2, i); |
| failures += testLog1pCase(d, d); |
| failures += testLog1pCase(-d, -d); |
| } |
| |
| // For x > 2^53 log1p(x) ~= log(x) |
| for(int i = 53; i <= Double.MAX_EXPONENT; i++) { |
| double d = Math.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 = RandomFactory.getRandom(); |
| for(int i = 0; i < 1000; i++) { |
| double d = rand.nextDouble(); |
| |
| d = Math.scalb(d, -53 - Tests.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] = Math.nextDown(pc); |
| pcNeighbors[0] = Math.nextDown(pcNeighbors[1]); |
| pcNeighbors[3] = Math.nextUp(pc); |
| pcNeighbors[4] = Math.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(); |
| } |
| } |
| } |