program circ_breathe_n_waltz
      integer pgopen
      if( pgopen('/xwin') <= 0 ) stop
      xmin=-2.0
      xmax= 2.0
      ymin=-2.0
      ymax= 2.0
      call pgenv(xmin,xmax,ymin,ymax,1,-1)
      x=0.0
      y=0.0
      dtheta = 2*3.14159/36000
      theta = 0.0
      rold = 1.0
c define initial x_old like r_old
      XOLD = X
      YOLD = y
      call pgsfs(2)
      do i=1,500000
        theta = theta + dtheta
        r = 1.0 + 0.25*sin(theta)
        X = 0.7*COS(THETA)
        Y = 0.7*SIN(THETA)
        call pgbbuf
         call pgsci(0)
c        call pgcirc(x,y,rold)
         call pgcirc(XOLD,YOLD,rold)
         call pgsci(1)
         call pgcirc(x,y,r)
        call pgebuf
        rold = r
        XOLD = X
        YOLD = Y
      end do
      call pgclos
      end