private static StableSampler create()

in commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/distribution/StableSampler.java [1397:1445]
27 lines of code
9 McCabe index (conditional complexity)

    private static StableSampler create(UniformRandomProvider rng,
                                        double alpha,
                                        double beta) {
        // Choose the algorithm.
        // The special case samplers have transformation support and use gamma=1.0, delta=0.0.
        // As alpha -> 0 the computation increasingly requires correction
        // of infinity to the distribution support.

        if (alpha == ALPHA_GAUSSIAN) {
            // Note: beta has no effect and is ignored.
            return new GaussianStableSampler(rng, GAMMA_1, DELTA_0);
        }

        // Note: As beta -> 0 the result cannot be computed differently to beta = 0.
        // This is based on the computation factor tau:
        final double tau = CMSStableSampler.getTau(alpha, beta);

        if (tau == TAU_ZERO) {
            // Symmetric case (beta skew parameter is effectively zero)
            if (alpha == ALPHA_CAUCHY) {
                return new CauchyStableSampler(rng, GAMMA_1, DELTA_0);
            }
            if (alpha <= ALPHA_SMALL) {
                // alpha -> 0 requires robust error correction
                return new Beta0WeronStableSampler(rng, alpha);
            }
            return new Beta0CMSStableSampler(rng, alpha);
        }

        // Here beta is significant.

        if (alpha == 1) {
            return new Alpha1CMSStableSampler(rng, beta);
        }

        if (alpha == ALPHA_LEVY && Math.abs(beta) == BETA_LEVY) {
            // Support mirroring for negative beta by inverting the beta=1 Levy sample
            // using a negative gamma. Note: The delta is not mirrored as it is a shift
            // applied to the scaled and mirrored distribution.
            return new LevyStableSampler(rng, beta, DELTA_0);
        }

        if (alpha <= ALPHA_SMALL) {
            // alpha -> 0 requires robust error correction
            return new WeronStableSampler(rng, alpha, beta);
        }

        return new CMSStableSampler(rng, alpha, beta);
    }