Hi William,
> >> Isn't the following a bug ?
> >>
> >> sage: mat = matrix(ZZ, [[1,1],[1,1]], sparse=False)
> >> sage: type(mat)
> >> <type 'sage.matrix.matrix_integer_dense.Matrix_integer_dense'>
> >> sage: mat2 = matrix(ZZ, mat, sparse=True)
>
> I didn't know you could even give a matrix as the input to the matrix
> constructor. If you type "matrix?" you'll see that of the many types
> of input that matrix takes, a matrix itself is definitely not one of
> them... however the docs specifically say:
>
> "Calling matrix() with a Sage object may return something that makes
> sense."
>
> That's what's happening here -- your matrix "mat" is just some sage
> object that has an "_matrix_" method. It's calling that method on
> mat. That method doesn't even take a sparse parameter.
>
> So technically the behavior you're seeing agrees with the stated
> documentation, so isn't a bug. However, I can see how it could be
> misleading! But fixing it could be a can of worms, so... thank you.
My American language is not very good... I'm not sure what you mean by "could
be a can of worms, so... thank you". Anyway, I'm ok fixing it if it is not too
complicated. Specifically, I'm ready to put a patch which calls the
constructor of MatrixSpace as in
sage: mat = matrix(ZZ, [[1,1],[1,1]], sparse=False)
sage: type(mat)
<type 'sage.matrix.matrix_integer_dense.Matrix_integer_dense'>
sage: res = MatrixSpace(ZZ, 2, 2, sparse=True)(mat)
sage: type(res)
<type 'sage.matrix.matrix_integer_sparse.Matrix_integer_sparse'>
Is it ok ?
Cheers,
Florent
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