Task: Julia set
C: #include<graphics.h>
#include<stdlib.h>
#include<math.h>

typedef struct{
	double x,y;
}complex;

complex add(complex a,complex b){
	complex c;
	c.x = a.x + b.x;
	c.y = a.y + b.y;
	return c;
}

complex sqr(complex a){
	complex c;
	c.x = a.x*a.x - a.y*a.y;
	c.y = 2*a.x*a.y;
	return c;
}

double mod(complex a){
	return sqrt(a.x*a.x + a.y*a.y);
}

complex mapPoint(int width,int height,double radius,int x,int y){
	complex c;
	int l = (width<height)?width:height;
	
	c.x = 2*radius*(x - width/2.0)/l;
	c.y = 2*radius*(y - height/2.0)/l;
	
	return c;
}

void juliaSet(int width,int height,complex c,double radius,int n){
	int x,y,i;
	complex z0,z1;
	
	for(x=0;x<=width;x++)
		for(y=0;y<=height;y++){
			z0 = mapPoint(width,height,radius,x,y);
			for(i=1;i<=n;i++){
				z1 = add(sqr(z0),c);
				if(mod(z1)>radius){
					putpixel(x,y,i%15+1);
					break;
				}
				z0 = z1;
			}
			if(i>n)
				putpixel(x,y,0);
		}
}

int main(int argC, char* argV[])
{
	int width, height;
	complex c;
	
	if(argC != 7)
		printf("Usage : %s <width and height of screen, real and imaginary parts of c, limit radius and iterations>");
	else{
		width = atoi(argV[1]);
		height = atoi(argV[2]);
		
		c.x = atof(argV[3]);
		c.y = atof(argV[4]);
		
		initwindow(width,height,"Julia Set");
		juliaSet(width,height,c,atof(argV[5]),atoi(argV[6]));
		
		getch();
	}
	
	return 0;
}

Java: import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;

public class JuliaSet extends JPanel {
    private static final int MAX_ITERATIONS = 300;
    private static final double ZOOM = 1;
    private static final double CX = -0.7;
    private static final double CY = 0.27015;
    private static final double MOVE_X = 0;
    private static final double MOVE_Y = 0;

    public JuliaSet() {
        setPreferredSize(new Dimension(800, 600));
        setBackground(Color.white);
    }

    void drawJuliaSet(Graphics2D g) {
        int w = getWidth();
        int h = getHeight();
        BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);

        for (int x = 0; x < w; x++) {
            for (int y = 0; y < h; y++) {
                double zx = 1.5 * (x - w / 2) / (0.5 * ZOOM * w) + MOVE_X;
                double zy = (y - h / 2) / (0.5 * ZOOM * h) + MOVE_Y;
                float i = MAX_ITERATIONS;
                while (zx * zx + zy * zy < 4 && i > 0) {
                    double tmp = zx * zx - zy * zy + CX;
                    zy = 2.0 * zx * zy + CY;
                    zx = tmp;
                    i--;
                }
                int c = Color.HSBtoRGB((MAX_ITERATIONS / i) % 1, 1, i > 0 ? 1 : 0);
                image.setRGB(x, y, c);
            }
        }
        g.drawImage(image, 0, 0, null);
    }

    @Override
    public void paintComponent(Graphics gg) {
        super.paintComponent(gg);
        Graphics2D g = (Graphics2D) gg;
        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);
        drawJuliaSet(g);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            JFrame f = new JFrame();
            f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            f.setTitle("Julia Set");
            f.setResizable(false);
            f.add(new JuliaSet(), BorderLayout.CENTER);
            f.pack();
            f.setLocationRelativeTo(null);
            f.setVisible(true);
        });
    }
}