class Samp8
{   
    static double f(double x)
    {
      double pi,fx;
      pi=Math.atan(1.0)*4.0;
      fx=Math.exp(-x)*Math.sin(4.0*pi*x);
      return(fx);
     }

    static void frame(PS ps1)
    {
     int ix,nx,iy,ny;double x,y,dx,dy;
     ps1.linewidth(1.0);
     ps1.rect(0.0,-1.0,1.0,1.0,0.0,1.0,1);
     nx=2;
     for (ix=1;ix<=nx*10-1;ix++){
      x=(double)ix/(double)(nx*10);dy=1.0;
        if(ix/10*10==ix) ps1.setgray(0.5);else ps1.setgray(0.8);
        ps1.plot(x,-dy,3);ps1.plot(x,dy,2);ps1.stroke();}
     ny=2;
     for (iy=1;iy<=ny*10-1;iy++){
      y=(double)iy/(double)(ny*10)*2.0-1.0;dx=1.0;
        if(iy/10*10==iy) ps1.setgray(0.5);else ps1.setgray(0.8);
        ps1.plot(0.0,y,3);ps1.plot(dx,y,2);ps1.stroke();}
     ps1.setgray(0.0);
     ps1.textx(0.75,0.0,1,"x");ps1.textx(0.05,0.02,1,"0");ps1.textx(0.55,0.02,3,"O.5");
     ps1.textx(0.95,0.02,1,"1");
     ps1.texty(0.0,0.5,1,"y");ps1.texty(0.0,-1.0,2,"-1");ps1.texty(0.0,0.0,1,"0");
     ps1.texty(0.0,1.0,1,"1");
    }

     static void plotd(PS ps1)
      {
        double [] x1=new double[21]; double [] y1=new double[21];int n,i;
 
        n=20; 
        for (i=0;i<=n;i++){
          x1[i]=(double)i/(double)n; y1[i] = f(x1[i]);}
        ps1.linewidth(1.5);ps1.linety(1);
        ps1.setgray(0.0);
        ps1.plot(x1[0],y1[0],3);
        for (i=1;i<=n-2;i++){
          ps1.spline1(x1[i-1],y1[i-1],x1[i],y1[i],x1[i+1],y1[i+1],x1[i+2],y1[i+2],-1);}
        ps1.spline1(x1[n-3],y1[n-3],x1[n-2],y1[n-2],x1[n-1],y1[n-1],x1[n],y1[n],0);
        ps1.spline1(x1[n-3],y1[n-3],x1[n-2],y1[n-2],x1[n-1],y1[n-1],x1[n],y1[n],1);
        ps1.stroke();
         }

    public static void main(String args[])
      {  
       PS ps1= new PS();
       ps1.init();
       ps1.viewport(0.2, 0.2, 0.8, 0.6);
       ps1.xyworld(0.0, -1.0, 1.0, 1.0);
       frame(ps1);
       plotd(ps1);
       ps1.fin(); 
     }
}