Converted by
Mathematica
June 8, 2001
![[Graphics:../Images/Pratica6_gr_50.gif]](../Images/Pratica6_gr_50.gif)
![[Graphics:../Images/Pratica6_gr_51.gif]](../Images/Pratica6_gr_51.gif)
![[Graphics:../Images/Pratica6_gr_52.gif]](../Images/Pratica6_gr_52.gif)