On Wed, Mar 26, 2008 at 11:01 AM, Jason Grout
[EMAIL PROTECTED] wrote:
Ryan Hinton brought up a good point at #2651:
Currently, matrix(3,{(1,1): 2}) gives the 3x2 sparse matrix
[0 0]
[0 2]
[0 0]
However, for other cases, if we specify just the number of rows, the
returned matrix is square (except when we are giving all the entries of
the matrix and there aren't enough entries). So:
Should the above command return the following instead?
[0 0 0]
[0 2 0]
[0 0 0]
Sorry for bringing up the nitpicky corner cases, but since matrix() is
used in a huge number of things, we don't want to mess something up when
we replace the constructor.
I very strongly agree that the output of matrix(3,{(1,1): 2}) should be the
sparse matrix:
[0 0 0]
[0 2 0]
[0 0 0]
BTW, there should be an example in the docstring for matrix that illustrates
how to make a dense matrix given a dictionary as input. E.g.,
sage: matrix(2,{(1,1):5},sparse=False).parent()
Full MatrixSpace of 2 by 2 dense matrices over Integer Ring
-- William
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