Converted by
Mathematica
June 17, 2001
![[Graphics:../Images/Pratica7_gr_65.gif]](../Images/Pratica7_gr_65.gif)
![[Graphics:../Images/Pratica7_gr_66.gif]](../Images/Pratica7_gr_66.gif)
![[Graphics:../Images/Pratica7_gr_67.gif]](../Images/Pratica7_gr_67.gif)