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/*
* Copyright (c) 2003, 2022, 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 HypotTests
* @bug 4851638 4939441 8078672 8240632
* @summary Tests for {Math, StrictMath}.hypot (use -Dseed=X to set PRNG seed)
* @key randomness
*/
import jdk.test.lib.RandomFactory;
public class HypotTests {
private HypotTests(){}
static final double infinityD = Double.POSITIVE_INFINITY;
static final double NaNd = Double.NaN;
/**
* Given integers m and n, assuming m < n, the triple (n^2 - m^2,
* 2mn, and n^2 + m^2) is a Pythagorean triple with a^2 + b^2 =
* c^2. This methods returns a long array holding the Pythagorean
* triple corresponding to the inputs.
*/
static long [] pythagoreanTriple(int m, int n) {
long M = m;
long N = n;
long result[] = new long[3];
result[0] = Math.abs(M*M - N*N);
result[1] = Math.abs(2*M*N);
result[2] = Math.abs(M*M + N*N);
return result;
}
static int testHypot() {
int failures = 0;
double [][] testCases = {
// Special cases
{infinityD, infinityD, infinityD},
{infinityD, 0.0, infinityD},
{infinityD, 1.0, infinityD},
{infinityD, NaNd, infinityD},
{NaNd, NaNd, NaNd},
{0.0, NaNd, NaNd},
{1.0, NaNd, NaNd},
{Double.longBitsToDouble(0x7FF0000000000001L), 1.0, NaNd},
{Double.longBitsToDouble(0xFFF0000000000001L), 1.0, NaNd},
{Double.longBitsToDouble(0x7FF8555555555555L), 1.0, NaNd},
{Double.longBitsToDouble(0xFFF8555555555555L), 1.0, NaNd},
{Double.longBitsToDouble(0x7FFFFFFFFFFFFFFFL), 1.0, NaNd},
{Double.longBitsToDouble(0xFFFFFFFFFFFFFFFFL), 1.0, NaNd},
{Double.longBitsToDouble(0x7FFDeadBeef00000L), 1.0, NaNd},
{Double.longBitsToDouble(0xFFFDeadBeef00000L), 1.0, NaNd},
{Double.longBitsToDouble(0x7FFCafeBabe00000L), 1.0, NaNd},
{Double.longBitsToDouble(0xFFFCafeBabe00000L), 1.0, NaNd},
};
for(int i = 0; i < testCases.length; i++) {
failures += testHypotCase(testCases[i][0], testCases[i][1],
testCases[i][2]);
}
// Verify hypot(x, 0.0) is close to x over the entire exponent
// range.
for(int i = DoubleConsts.MIN_SUB_EXPONENT;
i <= Double.MAX_EXPONENT;
i++) {
double input = Math.scalb(2, i);
failures += testHypotCase(input, 0.0, input);
}
// Test Pythagorean triples
// Small ones
for(int m = 1; m < 10; m++) {
for(int n = m+1; n < 11; n++) {
long [] result = pythagoreanTriple(m, n);
failures += testHypotCase(result[0], result[1], result[2]);
}
}
// Big ones
for(int m = 100000; m < 100100; m++) {
for(int n = m+100000; n < 200200; n++) {
long [] result = pythagoreanTriple(m, n);
failures += testHypotCase(result[0], result[1], result[2]);
}
}
// Approaching overflow tests
/*
* Create a random value r with an large-ish exponent. The
* result of hypot(3*r, 4*r) should be approximately 5*r. (The
* computation of 4*r is exact since it just changes the
* exponent). While the exponent of r is less than or equal
* to (MAX_EXPONENT - 3), the computation should not overflow.
*/
java.util.Random rand = RandomFactory.getRandom();
for(int i = 0; i < 1000; i++) {
double d = rand.nextDouble();
// Scale d to have an exponent equal to MAX_EXPONENT -15
d = Math.scalb(d, Double.MAX_EXPONENT
-15 - Tests.ilogb(d));
for(int j = 0; j <= 13; j += 1) {
failures += testHypotCase(3*d, 4*d, 5*d, 2.5);
d *= 2.0; // increase exponent by 1
}
}
// Test for monotonicity failures. Fix one argument and 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 hypot(pcNeighbors[i]) <= hypot(pcNeighbors[i+1])
{
double pcNeighbors[] = new double[5];
double pcNeighborsHypot[] = new double[5];
double pcNeighborsStrictHypot[] = new double[5];
for(int i = -18; i <= 18; i++) {
double pc = Math.scalb(1.0, i);
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++) {
pcNeighborsHypot[j] = Math.hypot(2.0, pcNeighbors[j]);
pcNeighborsStrictHypot[j] = StrictMath.hypot(2.0, pcNeighbors[j]);
}
for(int j = 0; j < pcNeighborsHypot.length-1; j++) {
if(pcNeighborsHypot[j] > pcNeighborsHypot[j+1] ) {
failures++;
System.err.println("Monotonicity failure for Math.hypot on " +
pcNeighbors[j] + " and " +
pcNeighbors[j+1] + "\n\treturned " +
pcNeighborsHypot[j] + " and " +
pcNeighborsHypot[j+1] );
}
if(pcNeighborsStrictHypot[j] > pcNeighborsStrictHypot[j+1] ) {
failures++;
System.err.println("Monotonicity failure for StrictMath.hypot on " +
pcNeighbors[j] + " and " +
pcNeighbors[j+1] + "\n\treturned " +
pcNeighborsStrictHypot[j] + " and " +
pcNeighborsStrictHypot[j+1] );
}
}
}
}
return failures;
}
/**
* Verify +0.0 is returned if both arguments are zero.
*/
private static int testHypotZeros() {
return testHypotCase(0.0, 0.0, +0.0, 0.0);
}
static int testHypotCase(double input1, double input2, double expected) {
return testHypotCase(input1,input2, expected, 1);
}
static int testHypotCase(double input1, double input2, double expected,
double ulps) {
int failures = 0;
if (expected < 0.0) {
throw new AssertionError("Result of hypot must be greater than " +
"or equal to zero");
}
// Test Math and StrictMath methods with no inputs negated,
// each input negated singly, and both inputs negated. Also
// test inputs in reversed order.
for(int i = -1; i <= 1; i += 2) {
for(int j = -1; j <= 1; j += 2) {
double x = i * input1;
double y = j * input2;
failures += Tests.testUlpDiff("Math.hypot", x, y, Math::hypot, expected, ulps);
failures += Tests.testUlpDiff("Math.hypot", y, x, Math::hypot, expected, ulps);
failures += Tests.testUlpDiff("StrictMath.hypot", x, y, StrictMath::hypot, expected, ulps);
failures += Tests.testUlpDiff("StrictMath.hypot", y, x, StrictMath::hypot, expected, ulps);
}
}
return failures;
}
public static void main(String... argv) {
int failures = 0;
failures += testHypot();
failures += testHypotZeros();
if (failures > 0) {
System.err.println("Testing the hypot incurred "
+ failures + " failures.");
throw new RuntimeException();
}
}
}
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