program graph1
   implicit none
   call init
   call viewport(0.2,0.2,0.8,0.8)
   call xyworld(-1.2,-1.2,1.2,1.2)
   call frame
   call drawline
   call fin
   stop
   end

subroutine frame
   implicit none
   integer n,i
   real(4) x,y,dx,dy
   call setgray(0.2)
   call arrow(-1.1,0.0,1.1,0.0,0.02)
   call arrow(0.0,-1.1,0.0,1.1,0.02)
   call textx(1.15,0.03,'x')
   call texty(0.02,1.15,'y')
   call textx(-0.13,-0.0,'O')
   call textx(0.5,-0.0,'pi/2')
   call textx(1.0,-0.0,'pi')
   call textx(-0.5,-0.0,'-pi/2')
   call textx(-1.0,-0.0,'-pi')
   call texty(0.02,1.0,'1')
   call texty(0.02,0.5,'0.5')
   call texty(0.02,-0.5,'-0.5')
   call texty(0.02,-1.0,'-1')
   n=10
   do i=1,n
      x=0.1*real(i)
      if(i/5*5==i)then
         dy=0.02
      else
         dy=0.01
      end if
      call line(-x,-dy,-x,dy)
      call line(x,-dy,x,dy)
   end do
   do i=1,n
      y=0.1*real(i)
      if(i/5*5==i)then
         dx=0.02
      else
         dx=0.01
      end if
      call line(-dx,-y,dx,-y)
      call line(-dx,y,dx,y)
   end do
   return
   end

subroutine drawline
   implicit none
   integer i
   integer,parameter::nx=100
   real(4) x,y,t
   x=-1.0
   y=0.0
   call linewidth(1.5)
   call setgray(0.0)
   call plot(x,y,3)
   do i=-nx+1,nx
      t=real(i)/real(nx)
      x=t
      y=sin(t*3.14159)
      call plot(x,y,2)
   end do
   call stroke
   return
   end