package com.imsl.test.example.stat.distributions;

import com.imsl.math.PrintMatrix;
import com.imsl.math.PrintMatrixFormat;
import com.imsl.stat.distributions.RayleighPD;
import java.text.DecimalFormat;

/**
 * <p>
 * Evaluates the Rayleigh probability distribution.</p>
 * <p>
 * This example evaluates the Rayleigh density, gradient, and hessian for a small
 * sample of data.</p>
 *
 * @see <a href="RayleighPDEx1.java">Code</a>
 * @see <a href="doc-files/RayleighPDEx1.out">Output</a>
 */

public class RayleighPDEx1 {

    public static void main(String[] args) {

        double[] x = {0, 0.5, 1, 4, 9};
        RayleighPD rpd = new RayleighPD();

        double[] values = new double[x.length];
        for (int i = 0; i < x.length; i++) {
            values[i] = rpd.pdf(x[i], 3.0);
        }
        
        PrintMatrixFormat pmf = new PrintMatrixFormat();
        pmf.setNumberFormat(new DecimalFormat("0.00000000"));

        PrintMatrix pm = new PrintMatrix("Rayleigh(3.0) pdf values at x=");
        pm.print(pmf, x);

        pm.setTitle("f(x;3.0)=");
        pm.print(pmf, values);

        double[] gradient = rpd.getPDFGradientApproximation(x[2], 3.0);
        
        String title = String.format("Approximate gradient of f(x;3.0) at x= %1.8f",x[2]);
        pm.setTitle(title);
        pm.print(pmf, gradient);
        
        gradient = rpd.getPDFGradient(x[2], 3.0);
        
        title = String.format("Analytic gradient of f(x;3.0) at x= %1.8f",x[2]);
        pm.setTitle(title);
        pm.print(pmf, gradient);

        double[][] hessian = rpd.getPDFHessianApproximation(x[2], 3.0);
        
        title = String.format("Approximate Hessian of f(x;3.0) at x= %1.8f",x[2]);
        pm.setTitle(title);
        pm.print(pmf, hessian);
        
        hessian = rpd.getPDFHessian(x[2], 3.0);
        title = String.format("Analytic Hessian of f(x;3.0) at x= %1.8f",x[2]);
        pm.setTitle(title);
        pm.print(pmf, hessian);
    }
}