pro eff_pot
!P.MULTI=[0,2,1]

   readmatrix,aa,'plummer_2.dat'

   x1=aa(*,1)
   y1=aa(*,2)
   z1=aa(*,3)
   p1=aa(*,7)
   e1=aa(*,8)
   x2=aa(*,9)
   y2=aa(*,10)
   z2=aa(*,11)
   p2=aa(*,15)
   e2=aa(*,16)


   rr1=sqrt(x1*x1+y1*y1+z1*z1)
   rr2=sqrt(x2*x2+y2*y2+z2*z2)

   plot,x1,y1,xtit='x',ytit='y'
   oplot,x2,y2,col=50

   plot,rr1,p1,xtit='r',ytit='Pot_eff'
   oplot,rr2,p2,col=50  ;blue
   ;oplot,rr1,e2,col=100 ;light blue
   ;oplot,rr2,e2,col=200 ;orange

   write_png,'eff_pot.png',tvrd(/true)

end