/*************************************************************************

* Compilation: javac FunctionGraph.java

* Execution: java FunctionGraph

* Dependencies: StdDraw.java

*

* Plots the function y = sin(4x) + sin(20x) between x = 0 and x = pi

* by drawing N line segments.

*

*************************************************************************/

public class FunctionGraph {

public static void main(String[] args) {

// number of line segments to plot

int N = Integer.parseInt(args[0]);

// the function y = sin(4x) + sin(20x), sampled at N points

// between x = 0 and x = pi

double[] x = new double[N+1];

double[] y = new double[N+1];

for (int i = 0; i <= N; i++) {

x[i] = Math.PI * i / N;

y[i] = Math.sin(4*x[i]) + Math.sin(20*x[i]);

}

// rescale the coordinate system

StdDraw.setXscale(0, Math.PI);

StdDraw.setYscale(-2.0, +2.0);

// plot the approximation to the function

for (int i = 0; i < N; i++) {

StdDraw.line(x[i], y[i], x[i+1], y[i+1]);

}

}

}