A=matrix(QQ,[[1,2,-2,0],[2,3,-4,1],[-1,-2,0,2],[-0,2,5,3]])
A.add_multiple_of_row(1,0,-2)
A.add_multiple_of_row(2,0,1)
A.add_multiple_of_row(3,1,2)
A.rescale_row(3,0.2)
A.rescale_row(2,0.5)
A.add_multiple_of_row(3,2,1)
A.det()
B=matrix([[2,-1,0,0],[-1,2,-1,0],[0,-1,2,-1],[0,0,-1,-2]])
B.rescale_row(1,2)
B.add_multiple_of_row(1,0,1)
B.swap_rows(1,2)
B.add_multiple_of_row(2,1,3)
B.swap_rows(2,3)
B.add_multiple_of_row(3,2,4)
B.det()

Strang-4.2-4-U (last edited 2010-12-18 12:17:09 by 10)