FunctionGraph.java

Below is the syntax highlighted version of FunctionGraph.java from §3.3 Designing Data Types.

/******************************************************************************
 *  Compilation:  javac FunctionGraph.java
 *  Execution:    java FunctionGraph a b
 *  Dependencies: StdStats.java
 *
 *  Plots the function f in the interval [a, b].
 *
 *  % java FunctionGraph -4 4
 *
 ******************************************************************************/

public class FunctionGraph {

    // plots the function f in the interval [a, b] using n+1 evenly spaced points
    public static void plot(Function f, double a, double b, int n) {
        double[] y = new double[n+1];
        double delta = (b - a) / n;
        for (int i = 0; i <= n; i++)
            y[i] = f.evaluate(a + delta*i);
        StdStats.plotPoints(y);
        StdStats.plotLines(y);
    }



    // sample client program
    public static void main(String[] args) {
        double a = Double.parseDouble(args[0]);
        double b = Double.parseDouble(args[1]);
        Function f = new GaussianPDF();
        plot(f, a, b, 50);
    }

}