On Thursday 14 July 2011, Simon King wrote:
> Hi Martin,
>
> On 14 Jul., 13:26, Martin Albrecht <martinralbre...@googlemail.com>
>
> wrote:
> > Note that these operations are quadratic just as the conversion Sage =>
> > LinBox.
>
> I am a bit surprised. My impression from reading
> sage.matrix.matrix_modn_dense was that Sage stores the matrix data in
> LinBox format anyway. So, did I get the wrong impression?
Hi,
linbox.matrix_matrix_multiply
calls
linbox_modn_dense_matrix_matrix_multiply
from the LinBox SPKG (src/interfaces/sage/linbox.C)
which calls
static DenseMatrix<ModInt> linbox_new_modn_matrix(mod_int modulus, mod_int**
matrix, size_t nrows, si\
ze_t ncols) {
ModInt F((double)modulus);
DenseMatrix<ModInt> A ( F, nrows, ncols);
size_t i, j, k;
for (i=0; i < nrows; i++) {
for (j=0; j < ncols; j++) {
A.setEntry(i, j, (double)matrix[i][j]);
}
}
return A;
};
which copies the matrix to a new matrix A.
Cheers,
Martin
--
name: Martin Albrecht
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