test.uk.co.modularaudio.util.math.Float16Tester.java Source code

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Here is the source code for test.uk.co.modularaudio.util.math.Float16Tester.java

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/**
 *
 * Copyright (C) 2015 - Daniel Hams, Modular Audio Limited
 *                      daniel.hams@gmail.com
 *
 * Mad is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Mad 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Mad.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package test.uk.co.modularaudio.util.math;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.mahout.math.list.IntArrayList;
import org.apache.mahout.math.map.OpenIntLongHashMap;
import org.junit.Test;

import uk.co.modularaudio.util.math.Float16;
import uk.co.modularaudio.util.math.MathFormatter;

public class Float16Tester {
    private static Log log = LogFactory.getLog(Float16Tester.class.getName());

    @Test
    public void testFromFloat() {
        final float[] testFloats = new float[] { Float16.MAX_VALUE, Float16.MIN_VALUE,

                // Interesting values from an audio perspective
                -1.0f, -0.001f, -0.0001f, 0.0f, 0.0001f, 0.001f, 1.0f, -1.1f, -0.9f, 0.9f, 1.1f,

                // Some "steady" values
                0.1f, 0.125f, 0.2f, 0.25f, 0.3f, 0.4f, 0.5f, 0.6f, 0.7f, 0.75f, 0.8f, 0.825f,

                // And some values to examine precision
                192000.0f, 41000.0f, 22050.0f, Float.NaN, Float.NEGATIVE_INFINITY, Float.POSITIVE_INFINITY, };

        for (final float testFloat : testFloats) {
            final Float16 f16 = new Float16(testFloat);

            final float andBack = f16.asFloat();

            log.debug("OF(" + MathFormatter.slowFloatPrint(testFloat, 16, true) + ") F16("
                    + MathFormatter.slowFloatPrint(andBack, 16, true) + ")");
        }
    }

    @Test
    public void testHaveEnoughPrecision() {
        final int f16One = Float16.fromFloat(1.0f);

        final float teensyFloat = 1.0f / 1000000.0f;

        int testf16;
        float curTestFloat = 1.0f;
        do {
            curTestFloat -= teensyFloat;
            testf16 = Float16.fromFloat(curTestFloat);
        } while (testf16 == f16One);

        final float nextLargestToOne = Float16.fromInt(testf16);
        log.debug("The next largest f16 near to 1.0f16 is "
                + MathFormatter.slowFloatPrint(nextLargestToOne, 12, true));

        final float minDiffNearOne = 1.0f - nextLargestToOne;
        log.debug("This is a diff of " + MathFormatter.slowFloatPrint(minDiffNearOne, 12, true));

        final OpenIntLongHashMap f16ToCountMap = new OpenIntLongHashMap(50000);

        final double delta = minDiffNearOne;

        double valueToCheck = 1.0;

        while (valueToCheck >= 0.0) {
            final int f16 = Float16.fromFloat((float) valueToCheck);
            final long curValue = f16ToCountMap.get(f16);
            f16ToCountMap.put(f16, curValue + 1);

            valueToCheck -= delta;
        }
        final int f16Zero = Float16.fromFloat(0.0f);
        final long curValue = f16ToCountMap.get(f16Zero);
        f16ToCountMap.put(f16Zero, curValue + 1);

        final IntArrayList keyList = f16ToCountMap.keys();

        final int numUniqueValues = keyList.size();
        log.debug("Have " + numUniqueValues + " equidistant unique values between 0.0f16 and 1.0f16");
        for (int i = 0; i < numUniqueValues; ++i) {
            final int value = keyList.get(i);
            final float f16AsFloat = Float16.fromInt(value);
            final long count = f16ToCountMap.get(value);

            final boolean shouldPrint = (i < 10 || i > (numUniqueValues - 10));
            //         final boolean shouldPrint = count > 1;

            if (shouldPrint) {
                log.debug("For key f16(" + MathFormatter.slowFloatPrint(f16AsFloat, 12, true) + ") numHits(" + count
                        + ")");
            }
        }
    }

}