/*
* Copyright (c) 2012 The Broad Institute
* 
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
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* copy, modify, merge, publish, distribute, sublicense, and/or sell
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* Software is furnished to do so, subject to the following
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* 
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
* 
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

package org.broadinstitute.sting.utils;

import cern.jet.random.Normal;
import org.broadinstitute.sting.BaseTest;
import org.testng.Assert;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.Test;

import java.util.*;

/**
 * Basic unit test for MathUtils
 */
public class MathUtilsUnitTest extends BaseTest {
    @BeforeClass
    public void init() {
    }

    /**
     * Tests that we get unqiue values for the valid (non-null-producing) input space for {@link MathUtils#fastGenerateUniqueHashFromThreeIntegers(int, int, int)}.
     */
    @Test
    public void testGenerateUniqueHashFromThreePositiveIntegers() {
        logger.warn("Executing testGenerateUniqueHashFromThreePositiveIntegers");
        
        final Set<Long> observedLongs = new HashSet<Long>();
        for (short i = 0; i < Byte.MAX_VALUE; i++) {
            for (short j = 0; j < Byte.MAX_VALUE; j++) {
                for (short k = 0; k < Byte.MAX_VALUE; k++) {
                    final Long aLong = MathUtils.fastGenerateUniqueHashFromThreeIntegers(i, j, k);
                    //System.out.println(String.format("%s, %s, %s: %s", i, j, k, aLong));
                    Assert.assertTrue(observedLongs.add(aLong));
                }
            }
        }

        for (short i = Byte.MAX_VALUE; i <= Short.MAX_VALUE && i > 0; i += 128) {
            for (short j = Byte.MAX_VALUE; j <= Short.MAX_VALUE && j > 0; j += 128) {
                for (short k = Byte.MAX_VALUE; k <= Short.MAX_VALUE && k > 0; k += 128) {
                    final Long aLong = MathUtils.fastGenerateUniqueHashFromThreeIntegers(i, j, k);
                    // System.out.println(String.format("%s, %s, %s: %s", i, j, k, aLong));
                    Assert.assertTrue(observedLongs.add(aLong));
                }
            }
        }
    }

    /**
     * Tests that we get the right values from the binomial distribution
     */
    @Test
    public void testBinomialProbability() {
        logger.warn("Executing testBinomialProbability");

        Assert.assertEquals(MathUtils.binomialProbability(3, 2, 0.5), 0.375, 0.0001);
        Assert.assertEquals(MathUtils.binomialProbability(100, 10, 0.5), 1.365543e-17, 1e-18);
        Assert.assertEquals(MathUtils.binomialProbability(217, 73, 0.02), 4.521904e-67, 1e-68);
        Assert.assertEquals(MathUtils.binomialProbability(300, 100, 0.02), 9.27097e-91, 1e-92);
        Assert.assertEquals(MathUtils.binomialProbability(300, 150, 0.98), 6.462892e-168, 1e-169);
        Assert.assertEquals(MathUtils.binomialProbability(300, 120, 0.98), 3.090054e-221, 1e-222);
        Assert.assertEquals(MathUtils.binomialProbability(300, 112, 0.98), 2.34763e-236, 1e-237);
    }

    /**
     * Tests that we get the right values from the binomial distribution
     */
    @Test
    public void testCumulativeBinomialProbability() {
        logger.warn("Executing testCumulativeBinomialProbability");

        for (int j = 0; j < 2; j++) { // Test memoizing functionality, as well.
            final int numTrials = 10;
            for ( int i = 0; i < numTrials; i++ )
                Assert.assertEquals(MathUtils.binomialCumulativeProbability(numTrials, i, i), MathUtils.binomialProbability(numTrials, i), 1e-10, String.format("k=%d, n=%d", i, numTrials));
    
            Assert.assertEquals(MathUtils.binomialCumulativeProbability(10, 0, 2), 0.05468750, 1e-7);
            Assert.assertEquals(MathUtils.binomialCumulativeProbability(10, 0, 5), 0.62304687, 1e-7);
            Assert.assertEquals(MathUtils.binomialCumulativeProbability(10, 0, 10), 1.0, 1e-7);
        }
    }

    /**
     * Tests that we get the right values from the multinomial distribution
     */
    @Test
    public void testMultinomialProbability() {
        logger.warn("Executing testMultinomialProbability");

        int[] counts0 = {2, 0, 1};
        double[] probs0 = {0.33, 0.33, 0.34};
        Assert.assertEquals(MathUtils.multinomialProbability(counts0, probs0), 0.111078, 1e-6);

        int[] counts1 = {10, 20, 30};
        double[] probs1 = {0.25, 0.25, 0.50};
        Assert.assertEquals(MathUtils.multinomialProbability(counts1, probs1), 0.002870301, 1e-9);

        int[] counts2 = {38, 82, 50, 36};
        double[] probs2 = {0.25, 0.25, 0.25, 0.25};
        Assert.assertEquals(MathUtils.multinomialProbability(counts2, probs2), 1.88221e-09, 1e-10);

        int[] counts3 = {1, 600, 1};
        double[] probs3 = {0.33, 0.33, 0.34};
        Assert.assertEquals(MathUtils.multinomialProbability(counts3, probs3), 5.20988e-285, 1e-286);
    }

    /**
     * Tests that the random index selection is working correctly
     */
    @Test
    public void testRandomIndicesWithReplacement() {
        logger.warn("Executing testRandomIndicesWithReplacement");

        // Check that the size of the list returned is correct
        Assert.assertTrue(MathUtils.sampleIndicesWithReplacement(5, 0).size() == 0);
        Assert.assertTrue(MathUtils.sampleIndicesWithReplacement(5, 1).size() == 1);
        Assert.assertTrue(MathUtils.sampleIndicesWithReplacement(5, 5).size() == 5);
        Assert.assertTrue(MathUtils.sampleIndicesWithReplacement(5, 1000).size() == 1000);

        // Check that the list contains only the k element range that as asked for - no more, no less
        List<Integer> Five = new ArrayList<Integer>();
        Collections.addAll(Five, 0, 1, 2, 3, 4);
        List<Integer> BigFive = MathUtils.sampleIndicesWithReplacement(5, 10000);
        Assert.assertTrue(BigFive.containsAll(Five));
        Assert.assertTrue(Five.containsAll(BigFive));
    }

    /**
     * Tests that we get the right values from the multinomial distribution
     */
    @Test
    public void testSliceListByIndices() {
        logger.warn("Executing testSliceListByIndices");

        // Check that the list contains only the k element range that as asked for - no more, no less but now
        // use the index list to pull elements from another list using sliceListByIndices
        List<Integer> Five = new ArrayList<Integer>();
        Collections.addAll(Five, 0, 1, 2, 3, 4);
        List<Character> FiveAlpha = new ArrayList<Character>();
        Collections.addAll(FiveAlpha, 'a', 'b', 'c', 'd', 'e');
        List<Integer> BigFive = MathUtils.sampleIndicesWithReplacement(5, 10000);
        List<Character> BigFiveAlpha = MathUtils.sliceListByIndices(BigFive, FiveAlpha);
        Assert.assertTrue(BigFiveAlpha.containsAll(FiveAlpha));
        Assert.assertTrue(FiveAlpha.containsAll(BigFiveAlpha));
    }

    /**
     * Tests that we correctly compute mean and standard deviation from a stream of numbers
     */
    @Test
    public void testRunningAverage() {
        logger.warn("Executing testRunningAverage");

        int[] numbers = {1, 2, 4, 5, 3, 128, 25678, -24};
        MathUtils.RunningAverage r = new MathUtils.RunningAverage();

        for (int i = 0; i < numbers.length; i++)
            r.add((double) numbers[i]);

        Assert.assertEquals((long) numbers.length, r.observationCount());
        Assert.assertTrue(r.mean() - 3224.625 < 2e-10);
        Assert.assertTrue(r.stddev() - 9072.6515881128 < 2e-10);
    }

    @Test
    public void testLog10Gamma() {
        logger.warn("Executing testLog10Gamma");

        Assert.assertEquals(MathUtils.log10Gamma(4.0), 0.7781513, 1e-6);
        Assert.assertEquals(MathUtils.log10Gamma(10), 5.559763, 1e-6);
        Assert.assertEquals(MathUtils.log10Gamma(10654), 38280.53, 1e-2);
    }

    @Test
    public void testLog10BinomialCoefficient() {
        logger.warn("Executing testLog10BinomialCoefficient");
        // note that we can test the binomial coefficient calculation indirectly via Newton's identity
        // (1+z)^m = sum (m choose k)z^k
        double[] z_vals = new double[]{0.999,0.9,0.8,0.5,0.2,0.01,0.0001};
        int[] exponent = new int[]{5,15,25,50,100};
        for ( double z : z_vals ) {
            double logz = Math.log10(z);
            for ( int exp : exponent ) {
                double expected_log = exp*Math.log10(1+z);
                double[] newtonArray_log = new double[1+exp];
                for ( int k = 0 ; k <= exp; k++ ) {
                    newtonArray_log[k] = MathUtils.log10BinomialCoefficient(exp,k)+k*logz;
                }
                Assert.assertEquals(MathUtils.log10sumLog10(newtonArray_log),expected_log,1e-6);
            }
        }

        Assert.assertEquals(MathUtils.log10BinomialCoefficient(4, 2), 0.7781513, 1e-6);
        Assert.assertEquals(MathUtils.log10BinomialCoefficient(10, 3), 2.079181, 1e-6);
        Assert.assertEquals(MathUtils.log10BinomialCoefficient(103928, 119), 400.2156, 1e-4);
    }

    @Test
    public void testFactorial() {
        logger.warn("Executing testFactorial");
        Assert.assertEquals((int) MathUtils.factorial(4), 24);
        Assert.assertEquals((int) MathUtils.factorial(10), 3628800);
        Assert.assertEquals((int) MathUtils.factorial(12), 479001600);
    }

    @Test
    public void testLog10Factorial() {
        logger.warn("Executing testLog10Factorial");
        Assert.assertEquals(MathUtils.log10Factorial(4), 1.380211, 1e-6);
        Assert.assertEquals(MathUtils.log10Factorial(10), 6.559763, 1e-6);
        Assert.assertEquals(MathUtils.log10Factorial(12), 8.680337, 1e-6);
        Assert.assertEquals(MathUtils.log10Factorial(200), 374.8969, 1e-3);
        Assert.assertEquals(MathUtils.log10Factorial(12342), 45138.26, 1e-1);
        double log10factorial_small = 0;
        double log10factorial_middle = 374.8969;
        double log10factorial_large = 45138.26;
        int small_start = 1;
        int med_start = 200;
        int large_start = 12342;
        for ( int i = 1; i < 1000; i++ ) {
            log10factorial_small += Math.log10(i+small_start);
            log10factorial_middle += Math.log10(i+med_start);
            log10factorial_large += Math.log10(i+large_start);
            Assert.assertEquals(MathUtils.log10Factorial(small_start+i),log10factorial_small,1e-6);
            Assert.assertEquals(MathUtils.log10Factorial(med_start+i),log10factorial_middle,1e-3);
            Assert.assertEquals(MathUtils.log10Factorial(large_start+i),log10factorial_large,1e-1);
        }
    }

    /**
     * Private functions used by testArrayShuffle()
     */
    private boolean hasUniqueElements(Object[] x) {
        for (int i = 0; i < x.length; i++)
            for (int j = i + 1; j < x.length; j++)
                if (x[i].equals(x[j]) || x[i] == x[j])
                    return false;
        return true;
    }

    private boolean hasAllElements(final Object[] expected, final Object[] actual) {
        HashSet<Object> set = new HashSet<Object>();
        set.addAll(Arrays.asList(expected));
        set.removeAll(Arrays.asList(actual));
        return set.isEmpty();
    }

    @Test
    public void testApproximateLog10SumLog10() {
        
        final double requiredPrecision = 1E-4;

        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {0.0}), 0.0, requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-5.15}), -5.15, requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {130.0}), 130.0, requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-0.145}), -0.145, requiredPrecision);

        Assert.assertEquals(MathUtils.approximateLog10SumLog10(0.0, 0.0), Math.log10(Math.pow(10.0, 0.0) + Math.pow(10.0, 0.0)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-1.0, 0.0), Math.log10(Math.pow(10.0, -1.0) + Math.pow(10.0, 0.0)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(0.0, -1.0), Math.log10(Math.pow(10.0, 0.0) + Math.pow(10.0, -1.0)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-2.2, -3.5), Math.log10(Math.pow(10.0, -2.2) + Math.pow(10.0, -3.5)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-1.0, -7.1), Math.log10(Math.pow(10.0, -1.0) + Math.pow(10.0, -7.1)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(5.0, 6.2), Math.log10(Math.pow(10.0, 5.0) + Math.pow(10.0, 6.2)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(38.1, 16.2), Math.log10(Math.pow(10.0, 38.1) + Math.pow(10.0, 16.2)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-38.1, 6.2), Math.log10(Math.pow(10.0, -38.1) + Math.pow(10.0, 6.2)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-19.1, -37.1), Math.log10(Math.pow(10.0, -19.1) + Math.pow(10.0, -37.1)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-29.1, -27.6), Math.log10(Math.pow(10.0, -29.1) + Math.pow(10.0, -27.6)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-0.12345, -0.23456), Math.log10(Math.pow(10.0, -0.12345) + Math.pow(10.0, -0.23456)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-15.7654, -17.0101), Math.log10(Math.pow(10.0, -15.7654) + Math.pow(10.0, -17.0101)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-0.12345, Double.NEGATIVE_INFINITY), -0.12345, requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-15.7654, Double.NEGATIVE_INFINITY), -15.7654, requiredPrecision);

        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {0.0, 0.0}), Math.log10(Math.pow(10.0, 0.0) + Math.pow(10.0, 0.0)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-1.0, 0.0}), Math.log10(Math.pow(10.0, -1.0) + Math.pow(10.0, 0.0)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {0.0, -1.0}), Math.log10(Math.pow(10.0, 0.0) + Math.pow(10.0, -1.0)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-2.2, -3.5}), Math.log10(Math.pow(10.0, -2.2) + Math.pow(10.0, -3.5)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-1.0, -7.1}), Math.log10(Math.pow(10.0, -1.0) + Math.pow(10.0, -7.1)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {5.0, 6.2}), Math.log10(Math.pow(10.0, 5.0) + Math.pow(10.0, 6.2)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {38.1, 16.2}), Math.log10(Math.pow(10.0, 38.1) + Math.pow(10.0, 16.2)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-38.1, 6.2}), Math.log10(Math.pow(10.0, -38.1) + Math.pow(10.0, 6.2)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-19.1, -37.1}), Math.log10(Math.pow(10.0, -19.1) + Math.pow(10.0, -37.1)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-29.1, -27.6}), Math.log10(Math.pow(10.0, -29.1) + Math.pow(10.0, -27.6)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-0.12345, -0.23456}), Math.log10(Math.pow(10.0, -0.12345) + Math.pow(10.0, -0.23456)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-15.7654, -17.0101}), Math.log10(Math.pow(10.0, -15.7654) + Math.pow(10.0, -17.0101)), requiredPrecision);

        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {0.0, 0.0, 0.0}), Math.log10(Math.pow(10.0, 0.0) + Math.pow(10.0, 0.0) + Math.pow(10.0, 0.0)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-1.0, 0.0, 0.0}), Math.log10(Math.pow(10.0, -1.0) + Math.pow(10.0, 0.0) + Math.pow(10.0, 0.0)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {0.0, -1.0, -2.5}), Math.log10(Math.pow(10.0, 0.0) + Math.pow(10.0, -1.0) + Math.pow(10.0, -2.5)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-2.2, -3.5, -1.1}), Math.log10(Math.pow(10.0, -2.2) + Math.pow(10.0, -3.5) + Math.pow(10.0, -1.1)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-1.0, -7.1, 0.5}), Math.log10(Math.pow(10.0, -1.0) + Math.pow(10.0, -7.1) + Math.pow(10.0, 0.5)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {5.0, 6.2, 1.3}), Math.log10(Math.pow(10.0, 5.0) + Math.pow(10.0, 6.2) + Math.pow(10.0, 1.3)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {38.1, 16.2, 18.1}), Math.log10(Math.pow(10.0, 38.1) + Math.pow(10.0, 16.2) + Math.pow(10.0, 18.1)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-38.1, 6.2, 26.6}), Math.log10(Math.pow(10.0, -38.1) + Math.pow(10.0, 6.2) + Math.pow(10.0, 26.6)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-19.1, -37.1, -45.1}), Math.log10(Math.pow(10.0, -19.1) + Math.pow(10.0, -37.1) + Math.pow(10.0, -45.1)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-29.1, -27.6, -26.2}), Math.log10(Math.pow(10.0, -29.1) + Math.pow(10.0, -27.6) + Math.pow(10.0, -26.2)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-0.12345, -0.23456, -0.34567}), Math.log10(Math.pow(10.0, -0.12345) + Math.pow(10.0, -0.23456) + Math.pow(10.0, -0.34567)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(new double[] {-15.7654, -17.0101, -17.9341}), Math.log10(Math.pow(10.0, -15.7654) + Math.pow(10.0, -17.0101) + Math.pow(10.0, -17.9341)), requiredPrecision);

        Assert.assertEquals(MathUtils.approximateLog10SumLog10(0.0, 0.0, 0.0), Math.log10(Math.pow(10.0, 0.0) + Math.pow(10.0, 0.0) + Math.pow(10.0, 0.0)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-1.0, 0.0, 0.0), Math.log10(Math.pow(10.0, -1.0) + Math.pow(10.0, 0.0) + Math.pow(10.0, 0.0)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(0.0, -1.0, -2.5), Math.log10(Math.pow(10.0, 0.0) + Math.pow(10.0, -1.0) + Math.pow(10.0, -2.5)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-2.2, -3.5, -1.1), Math.log10(Math.pow(10.0, -2.2) + Math.pow(10.0, -3.5) + Math.pow(10.0, -1.1)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-1.0, -7.1, 0.5), Math.log10(Math.pow(10.0, -1.0) + Math.pow(10.0, -7.1) + Math.pow(10.0, 0.5)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(5.0, 6.2, 1.3), Math.log10(Math.pow(10.0, 5.0) + Math.pow(10.0, 6.2) + Math.pow(10.0, 1.3)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(38.1, 16.2, 18.1), Math.log10(Math.pow(10.0, 38.1) + Math.pow(10.0, 16.2) + Math.pow(10.0, 18.1)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-38.1, 6.2, 26.6), Math.log10(Math.pow(10.0, -38.1) + Math.pow(10.0, 6.2) + Math.pow(10.0, 26.6)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-19.1, -37.1, -45.1), Math.log10(Math.pow(10.0, -19.1) + Math.pow(10.0, -37.1) + Math.pow(10.0, -45.1)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-29.1, -27.6, -26.2), Math.log10(Math.pow(10.0, -29.1) + Math.pow(10.0, -27.6) + Math.pow(10.0, -26.2)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-0.12345, -0.23456, -0.34567), Math.log10(Math.pow(10.0, -0.12345) + Math.pow(10.0, -0.23456) + Math.pow(10.0, -0.34567)), requiredPrecision);
        Assert.assertEquals(MathUtils.approximateLog10SumLog10(-15.7654, -17.0101, -17.9341), Math.log10(Math.pow(10.0, -15.7654) + Math.pow(10.0, -17.0101) + Math.pow(10.0, -17.9341)), requiredPrecision);

        // magnitude of the sum doesn't matter, so we can combinatorially test this via partitions of unity
        double[] mult_partitionFactor = new double[]{0.999,0.98,0.95,0.90,0.8,0.5,0.3,0.1,0.05,0.001};
        int[] n_partitions = new int[] {2,4,8,16,32,64,128,256,512,1028};
        for ( double alpha : mult_partitionFactor ) {
            double log_alpha = Math.log10(alpha);
            double log_oneMinusAlpha = Math.log10(1-alpha);
            for ( int npart : n_partitions ) {
                double[] multiplicative = new double[npart];
                double[] equal = new double[npart];
                double remaining_log = 0.0;  // realspace = 1
                for ( int i = 0 ; i < npart-1; i++ ) {
                    equal[i] = -Math.log10(npart);
                    double piece = remaining_log + log_alpha; // take a*remaining, leaving remaining-a*remaining = (1-a)*remaining
                    multiplicative[i] = piece;
                    remaining_log = remaining_log + log_oneMinusAlpha;
                }
                equal[npart-1] = -Math.log10(npart);
                multiplicative[npart-1] = remaining_log;
                Assert.assertEquals(MathUtils.approximateLog10SumLog10(equal),0.0,requiredPrecision,String.format("Did not sum to one: k=%d equal partitions.",npart));
                Assert.assertEquals(MathUtils.approximateLog10SumLog10(multiplicative),0.0,requiredPrecision, String.format("Did not sum to one: k=%d multiplicative partitions with alpha=%f",npart,alpha));
            }
        }
    }

    @Test
    public void testLog10sumLog10() {
        final double requiredPrecision = 1E-14;

        final double log3 = 0.477121254719662;
        Assert.assertEquals(MathUtils.log10sumLog10(new double[]{0.0, 0.0, 0.0}), log3, requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {0.0, 0.0, 0.0}, 0), log3, requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[]{0.0, 0.0, 0.0}, 0, 3), log3, requiredPrecision);

        final double log2 = 0.301029995663981;
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {0.0, 0.0, 0.0}, 0, 2), log2, requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {0.0, 0.0, 0.0}, 0, 1), 0.0, requiredPrecision);

        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {0.0}), 0.0, requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-5.15}), -5.15, requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {130.0}), 130.0, requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-0.145}), -0.145, requiredPrecision);

        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {0.0, 0.0}), Math.log10(Math.pow(10.0, 0.0) + Math.pow(10.0, 0.0)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-1.0, 0.0}), Math.log10(Math.pow(10.0, -1.0) + Math.pow(10.0, 0.0)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {0.0, -1.0}), Math.log10(Math.pow(10.0, 0.0) + Math.pow(10.0, -1.0)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-2.2, -3.5}), Math.log10(Math.pow(10.0, -2.2) + Math.pow(10.0, -3.5)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-1.0, -7.1}), Math.log10(Math.pow(10.0, -1.0) + Math.pow(10.0, -7.1)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {5.0, 6.2}), Math.log10(Math.pow(10.0, 5.0) + Math.pow(10.0, 6.2)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {38.1, 16.2}), Math.log10(Math.pow(10.0, 38.1) + Math.pow(10.0, 16.2)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-38.1, 6.2}), Math.log10(Math.pow(10.0, -38.1) + Math.pow(10.0, 6.2)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-19.1, -37.1}), Math.log10(Math.pow(10.0, -19.1) + Math.pow(10.0, -37.1)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-29.1, -27.6}), Math.log10(Math.pow(10.0, -29.1) + Math.pow(10.0, -27.6)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-0.12345, -0.23456}), Math.log10(Math.pow(10.0, -0.12345) + Math.pow(10.0, -0.23456)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-15.7654, -17.0101}), Math.log10(Math.pow(10.0, -15.7654) + Math.pow(10.0, -17.0101)), requiredPrecision);

        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {0.0, 0.0, 0.0}), Math.log10(Math.pow(10.0, 0.0) + Math.pow(10.0, 0.0) + Math.pow(10.0, 0.0)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-1.0, 0.0, 0.0}), Math.log10(Math.pow(10.0, -1.0) + Math.pow(10.0, 0.0) + Math.pow(10.0, 0.0)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {0.0, -1.0, -2.5}), Math.log10(Math.pow(10.0, 0.0) + Math.pow(10.0, -1.0) + Math.pow(10.0, -2.5)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-2.2, -3.5, -1.1}), Math.log10(Math.pow(10.0, -2.2) + Math.pow(10.0, -3.5) + Math.pow(10.0, -1.1)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-1.0, -7.1, 0.5}), Math.log10(Math.pow(10.0, -1.0) + Math.pow(10.0, -7.1) + Math.pow(10.0, 0.5)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {5.0, 6.2, 1.3}), Math.log10(Math.pow(10.0, 5.0) + Math.pow(10.0, 6.2) + Math.pow(10.0, 1.3)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {38.1, 16.2, 18.1}), Math.log10(Math.pow(10.0, 38.1) + Math.pow(10.0, 16.2) + Math.pow(10.0, 18.1)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-38.1, 6.2, 26.6}), Math.log10(Math.pow(10.0, -38.1) + Math.pow(10.0, 6.2) + Math.pow(10.0, 26.6)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-19.1, -37.1, -45.1}), Math.log10(Math.pow(10.0, -19.1) + Math.pow(10.0, -37.1) + Math.pow(10.0, -45.1)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-29.1, -27.6, -26.2}), Math.log10(Math.pow(10.0, -29.1) + Math.pow(10.0, -27.6) + Math.pow(10.0, -26.2)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-0.12345, -0.23456, -0.34567}), Math.log10(Math.pow(10.0, -0.12345) + Math.pow(10.0, -0.23456) + Math.pow(10.0, -0.34567)), requiredPrecision);
        Assert.assertEquals(MathUtils.log10sumLog10(new double[] {-15.7654, -17.0101, -17.9341}), Math.log10(Math.pow(10.0, -15.7654) + Math.pow(10.0, -17.0101) + Math.pow(10.0, -17.9341)), requiredPrecision);

        // magnitude of the sum doesn't matter, so we can combinatorially test this via partitions of unity
        double[] mult_partitionFactor = new double[]{0.999,0.98,0.95,0.90,0.8,0.5,0.3,0.1,0.05,0.001};
        int[] n_partitions = new int[] {2,4,8,16,32,64,128,256,512,1028};
        for ( double alpha : mult_partitionFactor ) {
            double log_alpha = Math.log10(alpha);
            double log_oneMinusAlpha = Math.log10(1-alpha);
            for ( int npart : n_partitions ) {
                double[] multiplicative = new double[npart];
                double[] equal = new double[npart];
                double remaining_log = 0.0;  // realspace = 1
                for ( int i = 0 ; i < npart-1; i++ ) {
                    equal[i] = -Math.log10(npart);
                    double piece = remaining_log + log_alpha; // take a*remaining, leaving remaining-a*remaining = (1-a)*remaining
                    multiplicative[i] = piece;
                    remaining_log = remaining_log + log_oneMinusAlpha;
                }
                equal[npart-1] = -Math.log10(npart);
                multiplicative[npart-1] = remaining_log;
                Assert.assertEquals(MathUtils.log10sumLog10(equal),0.0,requiredPrecision);
                Assert.assertEquals(MathUtils.log10sumLog10(multiplicative),0.0,requiredPrecision,String.format("Did not sum to one: nPartitions=%d, alpha=%f",npart,alpha));
            }
        }
    }

    @Test
    public void testLogDotProduct() {
        Assert.assertEquals(MathUtils.logDotProduct(new double[]{-5.0,-3.0,2.0}, new double[]{6.0,7.0,8.0}),10.0,1e-3);
        Assert.assertEquals(MathUtils.logDotProduct(new double[]{-5.0}, new double[]{6.0}),1.0,1e-3);
    }

    @Test
    public void testNormalDistribution() {
        final double requiredPrecision = 1E-10;

        final Normal n = new Normal(0.0, 1.0, null);
        for( final double mu : new double[]{-5.0, -3.2, -1.5, 0.0, 1.2, 3.0, 5.8977} ) {
            for( final double sigma : new double[]{1.2, 3.0, 5.8977} ) {
                for( final double x : new double[]{-5.0, -3.2, -1.5, 0.0, 1.2, 3.0, 5.8977} ) {
                    n.setState(mu, sigma);
                    Assert.assertEquals(n.pdf(x), MathUtils.normalDistribution(mu, sigma, x), requiredPrecision);
                    Assert.assertEquals(Math.log10(n.pdf(x)), MathUtils.normalDistributionLog10(mu, sigma, x), requiredPrecision);
                }
            }
        }
    }
}