Potential.java in prograame

Potential.java

import java.awt.Color;

public class Potential 

{

 public static void main(String[] args) 

   {

        int N = StdIn.readInt();

        Charge[] a = new Charge[N];

        for (int k = 0; k < N; k++) 

           {

            double x0 = StdIn.readDouble();

            double y0 = StdIn.readDouble();

            double q0 = StdIn.readDouble();

            a[k] = new Charge(x0, y0, q0);

            }

        int SIZE = 800;

        Picture pic = new Picture(SIZE, SIZE);

        for (int i = 0; i < SIZE; i++) 

              {

                      for (int j = 0; j < SIZE; j++) 

                {

                double V = 0.0;

                for (int k = 0; k < N; k++) 

                {

                    double x = 1.0 * i / SIZE;

                    double y = 1.0 * j / SIZE;

                    V += a[k].potentialAt(x, y);

                }

                V = 128 + V / 2.0e10;

                int t = 0;

                if      (V <   0) t = 0;

                else if (V > 255) t = 255;

                else              t = (int) V;

                Color c = new Color(t, t, t);

                Color c = Color.getHSBColor(t / 255.0f, .9f, .9f);

                Color c = Color.getHSBColor(.75f*t/40, .8f, .8f);

                int gray = (t * 37) % 255;

                Color c = new Color(gray, gray, gray);

                pic.set(i, SIZE-1-j, c);

            }

        }

        pic.show();

    }

}