Quelle  Rint.java   Sprache: JAVA

/*
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 * 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).
 *
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/*
 * @test
 * @bug 4101566 4831589
 * @summary Check for correct implementation of Math.rint(double)
 */

public class Rint {

    static int testRintCase(double input, double expected) {
        int failures = 0;
        double result;
        failures += Tests.test("Math.rint",        input, Math::rint,        expected);
        failures += Tests.test("Math.rint",       -input, Math::rint,       -expected);
        failures += Tests.test("StrictMath.rint",  input, StrictMath::rint,  expected);
        failures += Tests.test("StrictMath.rint", -input, StrictMath::rint, -expected);
        return failures;
    }

    public static void main(String... args) {
        int failures = 0;
        double twoToThe52 = Math.scalb(1.0, 52); // 2^52

        double [][] testCases = {
            {0.0,                               0.0},
            {Double.MIN_VALUE,                  0.0},
            {Math.nextDown(Double.MIN_NORMAL),  0.0},
            {Double.MIN_NORMAL,                 0.0},

            {0.2,                               0.0},

            {Math.nextDown(0.5),             0.0},
            {              0.5,              0.0},
            {  Math.nextUp(0.5),             1.0},

            {0.7,                               1.0},
            {Math.nextDown(1.0),             1.0},
            {              1.0,              1.0},
            {  Math.nextUp(1.0),             1.0},

            {Math.nextDown(1.5),             1.0},
            {              1.5,              2.0},
            {  Math.nextUp(1.5),             2.0},

            {4.2,                               4.0},
            {4.5,                               4.0},
            {4.7,                               5.0},

            {7.5,                               8.0},
            {7.2,                               7.0},
            {7.7,                               8.0},

            {150000.75,                         150001.0},
            {300000.5,                          300000.0},
            {Math.nextUp(300000.5),          300001.0},
            {Math.nextDown(300000.75),       300001.0},
            {300000.75,                         300001.0},
            {Math.nextUp(300000.75),         300001.0},
            {300000.99,                         300001.0},
            {262144.75,                         262145.0}, //(2^18 ) + 0.75
            {499998.75,                         499999.0},
            {524287.75,                         524288.0}, //(2^19 -1) + 0.75
            {524288.75,                         524289.0},

            {Math.nextDown(twoToThe52),      twoToThe52},
            {twoToThe52,                        twoToThe52},
            {Math.nextUp(twoToThe52),        Math.nextUp(twoToThe52)},

            {Double.MAX_VALUE,          Double.MAX_VALUE},
            {Double.POSITIVE_INFINITY,  Double.POSITIVE_INFINITY},
            {Double.NaN,                        Double.NaN}

        };

        for(int i = 0; i < testCases.length; i++) {
            failures += testRintCase(testCases[i][0], testCases[i][1]);
        }

        // Test values throughout exponent range
        for(double d = Double.MIN_VALUE;
            d < Double.POSITIVE_INFINITY; d *= 2) {
            failures += testRintCase(d, ((d<=0.5)?0.0:d));
        }

        if (failures > 0) {
            System.err.println("Testing {Math, StrictMath}.rint incurred "
                               + failures + " failures.");
            throw new RuntimeException();
        }
    }
}