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

import com.imsl.math.PrintMatrix;
import com.imsl.math.PrintMatrixFormat;
import com.imsl.stat.distributions.ExponentialPD;
import java.text.DecimalFormat;
/**
 * <p>
 * Evaluates the exponential probability distribution.</p>
 * <p>
 * This example evaluates the exponential density, gradient, and hessian for a small
 * sample of data.</p>
 *
 * @see <a href="ExponentialPDEx1.java">Code</a>
 * @see <a href="doc-files/ExponentialPDEx1.out">Output</a>
 */

public class ExponentialPDEx1 {

    public static void main(String[] args) {

        double[] x = {0.10309111631174948,4.033030873788534,0.7986927136384235,
            1.6898491466321743,0.5058626123268215,9.352583840240882,
            0.03869653643405882,1.5257326224511296,0.32818808182875037,
            2.8960165158175584};

        double scale = 3.0;
   
        ExponentialPD epd = new ExponentialPD();

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

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

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

        double[] gradient = epd.getPDFGradient(x[0],scale);

        String title=String.format("Gradient of f(x;3.0) at x= %1.8f",x[0]);
        pm.setTitle(title);
        pm.print(pmf, gradient);

        double[][] hessian = epd.getPDFHessian(x[0], scale);

        title=String.format("Hessian of f(x;3.0) at x= %1.8f",x[0]);
        pm.setTitle(title);
        pm.print(pmf, hessian);
    }
}