/*
 * 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 HypotTests
 * @bug 4851638 4939441 8078672
 * @summary Tests for {Math, StrictMath}.hypot (use -Dseed=X to set PRNG seed)
 * @author Joseph D. Darcy
 * @key randomness
 */
package test.java.lang.Math;

import java.util.Random;
import org.testng.annotations.Test;
import org.testng.Assert;

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;
    }

    @Test
    public void testHypot() {
        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 (double[] testCase : testCases) {
            testHypotCase(testCase[0], testCase[1], testCase[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);
            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);
                testHypotCase(result[0], result[1], result[2]);
            }
        }

        // Big ones
        // Android-changed: reduce test run time testing every 5th of original
        // for (int m = 100000; m < 100100; m++) {
        for (int m = 100000; m < 100100; m += 5) {
            // Android-changed: reduce test run time testing every 1000th of original
            // for (int n = m + 100000; n < 200200; n++) {
            for (int n = m + 100000; n < 200200; n += 1000) {
                long[] result = pythagoreanTriple(m, n);
                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 = new Random();
        // Android-changed: reduce test run time testing every 10th of original
        // for (int i = 0; i < 1000; i++) {
        for (int i = 0; i < 1000; i += 10) {
            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) {
                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]) {
                        Assert.fail("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]) {
                        Assert.fail("Monotonicity failure for StrictMath.hypot on " +
                                pcNeighbors[j] + " and " +
                                pcNeighbors[j + 1] + "\n\treturned " +
                                pcNeighborsStrictHypot[j] + " and " +
                                pcNeighborsStrictHypot[j + 1]);
                    }
                }
            }
        }
    }

    static void testHypotCase(double input1, double input2, double expected) {
        testHypotCase(input1, input2, expected, 1);
    }

    static void testHypotCase(double input1, double input2, double expected, double ulps) {
        if (expected < 0.0) {
            Assert.fail("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;
                Tests.testUlpDiff("Math.hypot", x, y,
                        Math.hypot(x, y), expected, ulps);
                Tests.testUlpDiff("Math.hypot", y, x,
                        Math.hypot(y, x), expected, ulps);

                Tests.testUlpDiff("StrictMath.hypot", x, y,
                        StrictMath.hypot(x, y), expected, ulps);
                Tests.testUlpDiff("StrictMath.hypot", y, x,
                        StrictMath.hypot(y, x), expected, ulps);
            }
        }
    }
}
