c     Plotting routine of equi-streamline in colors
      parameter (nx=200,ny=100)
      common /par/dx,dy
      call init
      call viewport(0.2,0.2,0.8,0.5)
      call xyworld(0.0,0.0,2.0,1.0)
      call frame
      call draw(1.0,-1.0,20)
      call frame
      call fin
      stop
      end
c
      subroutine frame
      call linewidth(1.0)
      call rect(0.0,0.0,2.0,1.0,0.0,1.0,1)
      nx=4
      do 10 ix=0,2*nx-1
       call setgray(0.0)
       x=float(ix)/float(nx)*2.0
       dy=0.05
       call plot(x,0.0,3)
       call plot(x,dy,2)
       call stroke()
   10 continue
      ny=2
      do 20 iy=0,ny-1
       call setgray(0.0)
       y=float(iy)/float(ny)
       dx=0.05
       call plot(0.0,y,3)
       call plot(dx,y,2)
       call stroke()
   20 continue
      call textx(1.5,0.0,1,'x')
      call textx(0.0,0.02,1,'0')
      call textx(1.0,0.02,1,'1')
      call textx(2.0,0.02,1,'2')
      call texty(0.0,0.75,1,'y')
      call texty(0.0,0.0,1,'0')
      call texty(0.0,0.5,3,'0.5')
      call texty(0.0,1.0,1,'1')
      return
      end
      function f(x,y)
       pi=3.14159
       f=sin(2.0*pi*x)*sin(pi*y)
      return
      end
      subroutine draw(fmax,fmin,nline)
      parameter (nx=200,ny=100)
      dx=2.0/float(nx)
      dy=1.0/float(ny)
      do 10 iy=1,ny
       y=float(iy)/float(ny)
       do 10 ix=1,nx
        x=float(ix)/float(nx)
          color=(f(x,y)-fmin)/(fmax-fmin)
	  call plot((ix-1)*dx,(iy-1)*dy,3)
	  call plot(ix*dx,(iy-1)*dy,2)
	  call plot(ix*dx,iy*dy,2)
	  call plot((ix-1)*dx,iy*dy,2)
	  write(1,*) ' closepath'
          r=color*0.8+0.2
          g=0.1
          b=(1.0-color)*0.8+0.2
          call setrgb(r,g,b)
         write(1,*) ' fill'
         write(1,*) ' stroke'
   10 continue
      return
      end