On 02/01/2010 08:12 AM, javier wrote:
You can see the source of the "minors" method using
sage: M.minors??
(you need to have defined M beforehand).
By browsing at that source one can easily find the general way of
doing it:
sage: A = Matrix(QQ, 3, [1,2,3,4,5,6,7,8,9])
sage: [A.matrix_from_rows_and_columns(rows, cols) for cols in
combinations_iterator(range(A.ncols()), 2) for rows in
combinations_iterator(range(A.nrows()),2)]
[
[1 2] [1 2] [4 5] [1 3] [1 3] [4 6] [2 3] [2 3] [5 6]
[4 5], [7 8], [7 8], [4 6], [7 9], [7 9], [5 6], [8 9], [8 9]
]
Or slightly easier to read:
sage: A = Matrix(QQ, 3, [1,2,3,4,5,6,7,8,9])
sage: [A[rows,cols] for cols in Combinations(A.ncols(),2) for rows in
Combinations(A.nrows(),2)]
[
[1 2] [1 2] [4 5] [1 3] [1 3] [4 6] [2 3] [2 3] [5 6]
[4 5], [7 8], [7 8], [4 6], [7 9], [7 9], [5 6], [8 9], [8 9]
]
Thanks,
Jason
--
Jason Grout
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