F=matrix([[1,2,-2,0],[2,3,-4,1],[-1,-2,0,2],[0,2,5,3]])
print F
G=F.echelon_form() 
print G.det()
H=matrix([[2,-1,0,0],[-1,2,-1,0],[0,-1,2,-1],[0,0,-1,-2]])
print H
I=H.echelon_form() 
print I.det()
H.swap_rows(2,3); H

Strang-4.2 4-U (last edited 2010-12-17 12:45:53 by 172)