program axisx
   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 xaxis(-1.0,0.0,1.0,0.0,2,10)
   call fin
   stop
   end

subroutine xaxis(x1,y1,x2,y2,m,n)
   implicit none
   real(4) x1,y1,x2,y2
   integer m,n
   integer i
   real(4) s,d,x,dx,dy
   call setgray(0.0)
   s=(x2-x1)*(x2-x1)+(y2-y1)*(y2-y1)
   s=sqrt(s)
   d=s/real(60)
   call arrow(x1-s/20.0,y1,x2+s/20.0*2.0,y2,d)
   do i=0,m*n
      x=1.0/real(m*n)*real(i)
      if(i/n*n==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
   call stroke
   call textx(x2+s/10.0*2.0,-s/30.0,'x')
   call textx((x1+x2)/2.0,(y1+y2)/2.0,'O')
   call textx(x2/2.0,y2,'pi/2')
   call textx(x2,y2,'pi')
   call textx(x1/2.0,y1,'-pi/2')
   call textx(x1,y1,'-pi')
   call stroke
   return
   end