commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/distribution/BoxMullerGaussianSampler.java [79:105]:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    @Override
    public double sample() {
        final double random;
        if (Double.isNaN(nextGaussian)) {
            // Generate a pair of Gaussian numbers.

            // Avoid zero for the uniform deviate y.
            // The extreme tail of the sample is:
            // y = 2^-53
            // r = 8.57167
            final double x = rng.nextDouble();
            final double y = InternalUtils.makeNonZeroDouble(rng.nextLong());
            final double alpha = 2 * Math.PI * x;
            final double r = Math.sqrt(-2 * Math.log(y));

            // Return the first element of the generated pair.
            random = r * Math.cos(alpha);

            // Keep second element of the pair for next invocation.
            nextGaussian = r * Math.sin(alpha);
        } else {
            // Use the second element of the pair (generated at the
            // previous invocation).
            random = nextGaussian;

            // Both elements of the pair have been used.
            nextGaussian = Double.NaN;
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -



commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/distribution/BoxMullerNormalizedGaussianSampler.java [52:78]:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    @Override
    public double sample() {
        final double random;
        if (Double.isNaN(nextGaussian)) {
            // Generate a pair of Gaussian numbers.

            // Avoid zero for the uniform deviate y.
            // The extreme tail of the sample is:
            // y = 2^-53
            // r = 8.57167
            final double x = rng.nextDouble();
            final double y = InternalUtils.makeNonZeroDouble(rng.nextLong());
            final double alpha = 2 * Math.PI * x;
            final double r = Math.sqrt(-2 * Math.log(y));

            // Return the first element of the generated pair.
            random = r * Math.cos(alpha);

            // Keep second element of the pair for next invocation.
            nextGaussian = r * Math.sin(alpha);
        } else {
            // Use the second element of the pair (generated at the
            // previous invocation).
            random = nextGaussian;

            // Both elements of the pair have been used.
            nextGaussian = Double.NaN;
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -