# Java Algorithms How to - Convert Plot polar function onto cartesian grid

## Question

We would like to know how to convert Plot polar function onto cartesian grid.

```import static java.lang.Math.PI;
import static java.lang.Math.cos;
import static java.lang.Math.log;
import static java.lang.Math.round;
import static java.lang.Math.sin;
import static java.lang.Math.tan;
//w  w  w.  ja va 2 s . c  o m
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.image.BufferedImage;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class Main {
public static void main(String[] args) {
final int width = 512;
final int height = 512;
BufferedImage img = new BufferedImage(width, height,
BufferedImage.TYPE_4BYTE_ABGR);
Graphics g = img.getGraphics();
g.setColor(Color.black);
g.fillRect(0, 0, width, height);
g.setColor(Color.white);
final double A = 8;
final double B = 0.5;
final double N = 4;
final double scale = 128;
final double zoom = 50;
final double step = 1 / scale;
Point last = null;
final Point origin = new Point(width / 2, height / 2);

for (double t = 0; t <= 2 * PI; t += step) {
final double r = zoom * polarFunction(t, A, B, N);
final int x = (int) round(r * cos(t));
final int y = (int) round(r * sin(t));
Point next = new Point(x, y);
if (last != null) {
g.drawLine(origin.x + last.x, origin.y + last.y, origin.x + next.x,
origin.y + next.y);
}
last = next;
}

JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);