Java Algorithms How to - Plot the sine and cosine functions

• Back to Math  ↑

Question

We would like to know how to plot the sine and cosine functions.

Answer

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Polygon;
//from  w  w  w .j  a  v  a 2 s.  co  m
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Main extends JFrame {
  public Main() {
    setLayout(new BorderLayout());
    add(new DrawSine(), BorderLayout.CENTER);
  }

  public static void main(String[] args) {
    Main frame = new Main();
    frame.setSize(400, 300);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
  }
}

class DrawSine extends JPanel {
  double f(double x) {
    return Math.sin(x);
  }

  double gCos(double y) {
    return Math.cos(y);
  }

  protected void paintComponent(Graphics g) {
    super.paintComponent(g);

    g.drawLine(10, 100, 380, 100);
    g.drawLine(200, 30, 200, 190);

    g.drawLine(380, 100, 370, 90);
    g.drawLine(380, 100, 370, 110);
    g.drawLine(200, 30, 190, 40);
    g.drawLine(200, 30, 210, 40);

    g.drawString("X", 360, 80);
    g.drawString("Y", 220, 40);

    Polygon p = new Polygon();
    Polygon p2 = new Polygon();

    for (int x = -170; x <= 170; x++) {
      p.addPoint(x + 200, 100 - (int) (50 * f((x / 100.0) * 2 * Math.PI)));

    }

    for (int x = -170; x <= 170; x++) {
      p2.addPoint(x + 200, 100 - (int) (50 * gCos((x / 100.0) * 2 * Math.PI)));

    }

    g.setColor(Color.red);
    g.drawPolyline(p.xpoints, p.ypoints, p.npoints);
    g.drawString("-2\u03c0", 95, 115);
    g.drawString("-\u03c0", 147, 115);
    g.drawString("\u03c0", 253, 115);
    g.drawString("2\u03c0", 305, 115);
    g.drawString("0", 200, 115);

    g.setColor(Color.blue);
    g.drawPolyline(p2.xpoints, p2.ypoints, p2.npoints);

  }
}

• Back to Math  ↑