Sage Reference Manual: Matrices and Spaces of Matrices - Mirrors

Sage Reference Manual: Matrices and Spaces of Matrices, Release 6.1.1
Traceback (most recent call last):
...
IndexError: column index out of range
columns(copy=True)
Return a list of the columns of self.
INPUT:
•copy - (default: True) if True, return a copy of the list of columns which is safe to change.
If self is a sparse matrix, columns are returned as sparse vectors, otherwise returned vectors are dense.
EXAMPLES:
sage: matrix(3, [1..9]).columns()
[(1, 4, 7), (2, 5, 8), (3, 6, 9)]
sage: matrix(RR, 2, [sqrt(2), pi, exp(1), 0]).columns()
[(1.41421356237310, 2.71828182845905), (3.14159265358979, 0.000000000000000)]
sage: matrix(RR, 0, 2, []).columns()
[(), ()]
sage: matrix(RR, 2, 0, []).columns()
[]
sage: m = matrix(RR, 3, 3, {(1,2): pi, (2, 2): -1, (0,1): sqrt(2)})
sage: parent(m.columns()[0])
Sparse vector space of dimension 3 over Real Field with 53 bits of precision
Sparse matrices produce sparse columns.
sage: A = matrix(QQ, 2, range(4), sparse=True)
sage: v = A.columns()[0]
sage: v.is_sparse()
True
TESTS:
sage: A = matrix(QQ, 4, range(16))
sage: A.columns(’junk’)
Traceback (most recent call last):
...
ValueError: ’copy’ must be True or False, not junk
delete_columns(dcols, check=True)
Return the matrix constructed from deleting the columns with indices in the dcols list.
INPUT:
•dcols - list of indices of columns to be deleted from self.
•check - checks whether any index in dcols is out of range. Defaults to True.
SEE ALSO: The methods delete_rows() and matrix_from_columns() are related.
EXAMPLES:
sage: A = Matrix(3,4,range(12)); A
[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]
sage: A.delete_columns([0,2])
[ 1 3]
101