I would suggest doing a quick search on github for any issues related to sparse matrices, and if none are relevant, opening a new one. One likely possibility is that neither function has been specialized for sparse matrices, and that the general fallback version of these functions are slow for sparse matrices. In either case, a specialized function should be easy to code.
Cheers, Kevin On Wed, Jan 7, 2015 at 9:20 AM, Christoph Ortner <[email protected] > wrote: > I don't have a solution, but a related comment: slicing of large sparse > matrices is very slow too. E.g., I like to assemble a stiffness matrix (for > a PDE) with free boundary conditions and then impose clamped boundaries by > taking a subset of the matrix, > B = A[Ifree, Ifree] > this is so slow that I had to completely give up on it and rewrite all my > assembly codes. > > I suspect that the flipxx functions and this are a similar issue? > > Is there already an issue filed for this? > > Christoph > >
