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package de.lmu.ifi.dbs.elki.math;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2015
Ludwig-Maximilians-Universität München
Lehr- und Forschungseinheit für Datenbanksysteme
ELKI Development Team
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program 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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import java.util.Random;
import org.junit.Test;
import de.lmu.ifi.dbs.elki.JUnit4Test;
/**
* Unit test for some basic math functions.
*
* @author Erich Schubert
*/
public class TestMathUtil implements JUnit4Test {
@Test
public void testPearsonCorrelation() {
final int size = 1000;
final long seed = 1;
double[] data1 = new double[size];
double[] data2 = new double[size];
double[] weight1 = new double[size];
double[] weight2 = new double[size];
Random r = new Random(seed);
for (int i = 0; i < size; i++) {
data1[i] = r.nextDouble();
data2[i] = r.nextDouble();
weight1[i] = 1.0;
weight2[i] = 0.1;
}
double pear = MathUtil.pearsonCorrelationCoefficient(data1, data2);
double wpear1 = MathUtil.weightedPearsonCorrelationCoefficient(data1, data2, weight1);
double wpear2 = MathUtil.weightedPearsonCorrelationCoefficient(data1, data2, weight2);
assertEquals("Pearson and weighted pearson should be the same with constant weights.", pear, wpear1, 1E-10);
assertEquals("Weighted pearsons should be the same with constant weights.", wpear1, wpear2, 1E-10);
}
@Test
public void testBitMath() {
assertEquals("Bit math issues", 1024, MathUtil.nextPow2Int(912));
assertEquals("Bit math issues", 8, MathUtil.nextPow2Int(5));
assertEquals("Bit math issues", 4, MathUtil.nextPow2Int(4));
assertEquals("Bit math issues", 4, MathUtil.nextPow2Int(3));
assertEquals("Bit math issues", 2, MathUtil.nextPow2Int(2));
assertEquals("Bit math issues", 1, MathUtil.nextPow2Int(1));
assertEquals("Bit math issues", 0, MathUtil.nextPow2Int(0));
assertEquals("Bit math issues", 1024L, MathUtil.nextPow2Long(912L));
assertEquals("Bit math issues", 0, MathUtil.nextPow2Int(-1));
assertEquals("Bit math issues", 0, MathUtil.nextPow2Int(-2));
assertEquals("Bit math issues", 0, MathUtil.nextPow2Int(-99));
assertEquals("Bit math issues", 15, MathUtil.nextAllOnesInt(8));
assertEquals("Bit math issues", 7, MathUtil.nextAllOnesInt(4));
assertEquals("Bit math issues", 3, MathUtil.nextAllOnesInt(3));
assertEquals("Bit math issues", 3, MathUtil.nextAllOnesInt(2));
assertEquals("Bit math issues", 1, MathUtil.nextAllOnesInt(1));
assertEquals("Bit math issues", 0, MathUtil.nextAllOnesInt(0));
assertEquals("Bit math issues", -1, MathUtil.nextAllOnesInt(-1));
assertEquals("Bit math issues", 0, 0 >>> 1);
}
@Test
public void testFloatToDouble() {
Random r = new Random(1l);
for (int i = 0; i < 10000; i++) {
final double dbl = Double.longBitsToDouble(r.nextLong());
final float flt = (float) dbl;
final double uppd = MathUtil.floatToDoubleUpper(flt);
final float uppf = (float) uppd;
final double lowd = MathUtil.floatToDoubleLower(flt);
final float lowf = (float) lowd;
assertTrue("Expected value to become larger, but " + uppd + " < " + dbl, uppd >= dbl || Double.isNaN(dbl));
assertTrue("Expected value to round to the same float.", flt == uppf || Double.isNaN(flt));
assertTrue("Expected value to become smaller, but " + lowd + " > " + dbl, lowd <= dbl || Double.isNaN(dbl));
assertTrue("Expected value to round to the same float.", flt == lowf || Double.isNaN(flt));
}
}
}
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