--- /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();
+ }
+ }
+
+}