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/*
* 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
*/
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 int testLog10Case(double input, double expected) {
int failures=0;
failures+=Tests.test("Math.log10(double)", input,
Math.log10(input), expected);
failures+=Tests.test("StrictMath.log10(double)", input,
StrictMath.log10(input), expected);
return failures;
}
static int testLog10() {
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, 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(int i = 0; i < testCases.length; i++) {
failures += testLog10Case(testCases[i][0],
testCases[i][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++) {
failures += 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) {
failures++;
System.err.println("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) {
failures++;
System.err.println("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) ) {
failures++;
System.err.println("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) ) {
failures++;
System.err.println("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] ) {
failures++;
System.err.println("Monotonicity failure for Math.log10 at " + input[i] +
" and prior value.");
}
if( neighborsStrict[i-1] > neighborsStrict[i] ) {
failures++;
System.err.println("Monotonicity failure for StrictMath.log10 at " + input[i] +
" and prior value.");
}
}
}
}
return failures;
}
public static void main(String argv[]) {
int failures = 0;
failures += testLog10();
if (failures > 0) {
System.err.println("Testing log10 incurred "
+ failures + " failures.");
throw new RuntimeException();
}
}
}
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