#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "ps.h"

double f(double);
void plotd(void);
void frame(void);

int main(void)
{    
     init();
     viewport(0.2, 0.2, 0.8, 0.6); 
     xyworld(0.0, -1.0, 1.0, 1.0); 
     frame();
     plotd();
     fin();

     return 0;
}

double f(double x) 
{    double pi,f1;
     pi=atan(1.0)*4.0;
     f1=exp(-x)*sin(4.0*pi*x);
     return (f1);
}

void plotd() 
{  double x1[21],y1[21];double x=1.0;
   int i,n=20;
     for (i=0;i<=n; i++) { x1[i]=(double)i/(double)n; 
                           y1[i]=f(x1[i]); } 
     linewidth(1.5);
     linety(1);
     setgray(0.0);
     plot(x1[0], y1[0], 3);
     for (i=1;i<=n-2;i++) {
       spline1(x1[i-1],y1[i-1],x1[i],y1[i],x1[i+1],y1[i+1],x1[i+2],y1[i+2],-1); }
     spline1(x1[n-3],y1[n-3],x1[n-2],y1[n-2],x1[n-1],y1[n-1],x1[n],y1[n],0);
     spline1(x1[n-3],y1[n-3],x1[n-2],y1[n-2],x1[n-1],y1[n-1],x1[n],y1[n],1);
     stroke();
}
void frame()
{
     double x,y,dx,dy; 
     int nx=2,ny=2,ix,iy;
      
       linewidth(1.0);
       rect(0.0, -1.0, 1.0, 1.0, 0.0, 1.0, 1);
       for(ix=1;ix<=nx*10-1;ix++) {
         x = (double)ix/((double) nx*10);
         dy=1.0;
         if(ix/10*10==ix) setgray(0.5); else setgray(0.8); 
         plot( x, -dy, 3);
         plot( x, dy, 2);
         stroke();               }
      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) setgray(0.5); else setgray(0.8);
         plot( 0.0, y, 3);
         plot( dx,  y, 2);
         stroke();               }
      setgray(0.0);
      textx(0.75, 0.0, 1, "x");
      textx(0.05, 0.02, 1, "0");
      textx(0.55, 0.02, 3, "0.5");
      textx(0.95, 0.02, 1, "1");
      texty(0.0, 0.5, 1, "y");
      texty(0.0, -1.0, 2, "-1");
      texty(0.0, 0.0, 1, "0");
      texty(0.0, 1.0, 1, "1");
     return;
}