Converted by
Mathematica
June 17, 2001
![[Graphics:../Images/Pratica7_gr_223.gif]](../Images/Pratica7_gr_223.gif)
![[Graphics:../Images/Pratica7_gr_224.gif]](../Images/Pratica7_gr_224.gif)
![[Graphics:../Images/Pratica7_gr_225.gif]](../Images/Pratica7_gr_225.gif)