Alright, so your point is that while this construction is in principal possible, it will not be efficient. Thanks for clearing this up!
On Tue, Apr 1, 2014 at 4:57 PM, Jed Brown <[email protected]> wrote: > Mathis Friesdorf <[email protected]> writes: > > > Thanks Jed, this is great. I was trying to implement what was proposed in > > > http://lists.mcs.anl.gov/pipermail/petsc-users/2011-September/009991.html, > > by you as I just realised. For this the matrices would be of varying > size, > > so for three local systems, I would need: > > > > S \otimes Id \otimes Id ; Id \otimes S \otimes Id ; Id \otimes Id > \otimes S. > > > > Realistic systems are of the order of at least 20 local systems, which > > would mean that I need the matrices of the above structure for all 20 > > possible positions. > > This is something for which you should use CTF or TCE. When S moves out > of the last position in the tensor product, the operation becomes less > local and various forms of transposition is needed. This is not > something worth recreating in PETSc unless there is a critical > deficiency in the available libraries. >
