/**
 * Initilizes the quadrature for calculating allele ratio integrals in
 * {@link HeterogeneousHeterozygousPileupPriorModel#getHetLogLikelihood(List)}
 *
 * @param numIntegPoints  number of points in the quadrature
 */
private void initializeIntegrationQuadrature(final int numIntegPoints) {
    /* get Gauss-Legendre quadrature factory of order @numIntegPoints */
    final GaussIntegratorFactory integratorFactory = new GaussIntegratorFactory();
    final GaussIntegrator gaussIntegrator = integratorFactory.legendre(numIntegPoints,
            minHetAlleleFraction, 1.0 - minHetAlleleFraction);

    /* abscissas */
    gaussIntegrationAbscissas.clear();
    gaussIntegrationAbscissas.addAll(IntStream.range(0, numIntegPoints).
            mapToDouble(gaussIntegrator::getPoint).boxed().collect(Collectors.toList()));

    /* weights */
    gaussIntegrationWeights.clear();
    gaussIntegrationWeights.addAll(IntStream.range(0, numIntegPoints).
            mapToDouble(gaussIntegrator::getWeight).boxed().collect(Collectors.toList()));

    /* log of weights */
    gaussIntegrationLogWeights.clear();
    gaussIntegrationLogWeights.addAll(gaussIntegrationWeights.stream().
            mapToDouble(FastMath::log).boxed().collect(Collectors.toList()));
}