On Fri, Aug 25, 2017 at 11:39 PM, Pauli Virtanen <pav@iki.fi> wrote:
pe, 2017-08-25 kello 23:08 -0700, Jonathan Taylor kirjoitti:
I've got a largeish array that I have saved in a .MAT file that I need to use for matvec multiply several times.
It seems that if I copy the array before running the matvec I get a significant speedup. Is this known?
If you do the copy in a way such that the format of the matrix is different (e.g. different sparse matrix format), then the speed can differ. Check print(type(original_matrix), type(copied_matrix)).
If it's a dense matrix, then it's also possible that the original matrix gets Fortran layout, and the copy is C layout. To test that you want: print(original_matrix.strides, copied_matrix.strides) -n -- Nathaniel J. Smith -- https://vorpus.org