C Plotting grogram for general purpose using PostScript
      program main
      call init
      call viewport(0.2, 0.2, 0.8, 0.6)
      call xyworld (0.0, -1.0, 1.0, 1.0)
      call frame
      call plotd
      call fin
      stop
      end
C
      function f(x) 
      pi=atan(1.0)*4.0
      f=exp(-x)*sin(4.0*pi*x)
      return
      end 
C
      subroutine plotd()
      dimension x1(0:20),y1(0:20)
      n=20
      do 10 i=0,n
       x1(i)=float(i)/float(n)
       y1(i)=f(x1(i))
   10 continue
      call linewidth(1.5)
      call linety(1)
      call setgray(0.0)
      call plot(x1(0), y1(0), 3)
      do 20 i=1, n-2
       call spline1(x1(i-1), y1(i-1), x1(i), y1(i), x1(i+1), y1(i+1), 
     &                x1(i+2), y1(i+2), -1)
   20 continue
      call spline1(x1(n-3), y1(n-3), x1(n-2), y1(n-2), x1(n-1), y1(n-1),
     &                x1(n), y1(n), 0)
      call spline1(x1(n-3), y1(n-3), x1(n-2), y1(n-2), x1(n-1), y1(n-1),
     &                x1(n), y1(n), 1)
      call stroke()
      return
      end
      subroutine frame
      call linewidth(1.0)
      call rect(0.0, -1.0, 1.0, 1.0, 0.0, 1.0, 1)
      nx=2
      do 30 ix = 1, nx*10-1
         x = float(ix)/float(nx*10)
         dy=1.0
         if(ix/10*10.eq.ix) then
            call setgray(0.5)
           else
            call setgray(0.8)
         end if
         call  plot( x, -dy, 3)
         call  plot( x, dy, 2)
         call stroke()
   30 continue
      ny=2
      do 40 iy = 1, ny*10-1
         y = float(iy)/float(ny*10)*2.0-1.0
         dx=1.0
         if(iy/10*10.eq.iy) then
            call setgray(0.5)
           else
            call setgray(0.8)
         end if
         call  plot( 0.0, y, 3)
         call  plot( dx,  y, 2)
         call stroke()
   40 continue
      call setgray(0.0)
      call textx(0.75, 0.0, 1, 'x')
      call textx(0.05, 0.02, 1, '0')
      call textx(0.55, 0.02, 3, '0.5')
      call textx(0.95, 0.02, 1, '1')
      call texty(0.0, 0.5, 1, 'y')
      call texty(0.0, -1.0, 2, '-1')
      call texty(0.0, 0.0, 1, '0')
      call texty(0.0, 1.0, 1, '1')
      return
      end