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

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

/**
 * <p>
 * Evaluates the Pareto probability distribution.</p>
 * <p>
 * This example evaluates the Pareto density, gradient, and hessian for a small
 * sample of data.</p>
 *
 * @see <a href="ParetoPDEx1.java">Code</a>
 * @see <a href="doc-files/ParetoPDEx1.out">Output</a>
 */

public class ParetoPDEx1 {

    public static void main(String[] args) {
        double[] x = {1, 2, 7, 20};
        ParetoPD ppd = new ParetoPD();

        double[] values = new double[x.length];
        for (int i = 0; i < x.length; i++) {
            values[i] = ppd.pdf(x[i], 1.0, 1.0);
        }
        PrintMatrixFormat pmf = new PrintMatrixFormat();
        pmf.setNumberFormat(new DecimalFormat("0.00000000"));

        PrintMatrix pm = new PrintMatrix("Pareto(1.0,1.0) pdf values at x=");
        pm.print(pmf, x);

        pm.setTitle("f(x;1.0,1.0)=");
        pm.print(pmf, values);

        double[] gradient = ppd.getPDFGradientApproximation(x[2], 1.0, 1.0);

        String title = String.format("Gradient of f(x;1.0,1.0) at x= %1.8f", x[2]);
        pm.setTitle(title);
        pm.print(pmf, gradient);

        double[][] hessian = ppd.getPDFHessianApproximation(x[2], 1.0, 1.0);

        title = String.format("Hessian of f(x;1.0,1.0) at x= %1.8f", x[2]);
        pm.setTitle(title);
        pm.print(pmf, hessian);
    }
}