Task: Mandelbrot set
C:  
 #include <stdio.h>
 #include <math.h>
 int main()
 {
          
        int iX,iY;
        const int iXmax = 800; 
        const int iYmax = 800;
        
        double Cx,Cy;
        const double CxMin=-2.5;
        const double CxMax=1.5;
        const double CyMin=-2.0;
        const double CyMax=2.0;
        
        double PixelWidth=(CxMax-CxMin)/iXmax;
        double PixelHeight=(CyMax-CyMin)/iYmax;
        
        
        const int MaxColorComponentValue=255; 
        FILE * fp;
        char *filename="new1.ppm";
        char *comment="# ";
        static unsigned char color[3];
        
        double Zx, Zy;
        double Zx2, Zy2; 
        
        int Iteration;
        const int IterationMax=200;
        
        const double EscapeRadius=2;
        double ER2=EscapeRadius*EscapeRadius;
        
        fp= fopen(filename,"wb"); 
        
        fprintf(fp,"P6\n %s\n %d\n %d\n %d\n",comment,iXmax,iYmax,MaxColorComponentValue);
        
        for(iY=0;iY<iYmax;iY++)
        {
             Cy=CyMin + iY*PixelHeight;
             if (fabs(Cy)< PixelHeight/2) Cy=0.0; 
             for(iX=0;iX<iXmax;iX++)
             {         
                        Cx=CxMin + iX*PixelWidth;
                        
                        Zx=0.0;
                        Zy=0.0;
                        Zx2=Zx*Zx;
                        Zy2=Zy*Zy;
                        
                        for (Iteration=0;Iteration<IterationMax && ((Zx2+Zy2)<ER2);Iteration++)
                        {
                            Zy=2*Zx*Zy + Cy;
                            Zx=Zx2-Zy2 +Cx;
                            Zx2=Zx*Zx;
                            Zy2=Zy*Zy;
                        };
                        
                        if (Iteration==IterationMax)
                        { 
                           color[0]=0;
                           color[1]=0;
                           color[2]=0;                           
                        }
                     else 
                        { 
                             color[0]=255; 
                             color[1]=255;   
                             color[2]=255;
                        };
                        
                        fwrite(color,1,3,fp);
                }
        }
        fclose(fp);
        return 0;
 }

Java: import java.awt.Graphics;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;

public class Mandelbrot extends JFrame {

    private final int MAX_ITER = 570;
    private final double ZOOM = 150;
    private BufferedImage I;
    private double zx, zy, cX, cY, tmp;

    public Mandelbrot() {
        super("Mandelbrot Set");
        setBounds(100, 100, 800, 600);
        setResizable(false);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        I = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB);
        for (int y = 0; y < getHeight(); y++) {
            for (int x = 0; x < getWidth(); x++) {
                zx = zy = 0;
                cX = (x - 400) / ZOOM;
                cY = (y - 300) / ZOOM;
                int iter = MAX_ITER;
                while (zx * zx + zy * zy < 4 && iter > 0) {
                    tmp = zx * zx - zy * zy + cX;
                    zy = 2.0 * zx * zy + cY;
                    zx = tmp;
                    iter--;
                }
                I.setRGB(x, y, iter | (iter << 8));
            }
        }
    }

    @Override
    public void paint(Graphics g) {
        g.drawImage(I, 0, 0, this);
    }

    public static void main(String[] args) {
        new Mandelbrot().setVisible(true);
    }
}