On Thu, 18 Aug 2005 20:50:12 -0500 (CDT) Barry Smith <bsmith at mcs.anl.gov> wrote:
> > Simon, > > There is not because what does MatSet() mean for a sparse matrix? > Make it dense, just set all the current nonzeros, error? You tell us, > I could live with either of the later two but don't really like the > first. Yes, it would be an error, that sounds the best to me. > > Barry > > BTW: possibly related note, are you using dense matrices sometimes > to represent "just" 2-arrays; that is, not as representations of linear > operators. If so, I do not think this is the correct approach! Conceptually > PETSc Mat's are linear operators I think it would be a big mistake to > overload them as 2-arrays also. The "correct" approach is to use the > DACreate2d() construct for handling 2-d arrays; With the DA the values > are stored into Vecs but there is additional information about > the two array structure; it can be decomposed nicely in parallel and > one can set/access values with the usual two i,j indices. Of course if > they are being used as operators ignore this. OK, I will think about this. But what would be the strategy for doing all these linear algebra operations ? Swap to/from Mat/DA objects ? Simon. > > In Matlab matrix == 2-d array == matrix (in my opinion a terrible design > decision) > in PETSc matrix (dense) != 2-d array , the are completely different > beasts mathematically > > > > On Fri, 19 Aug 2005, Simon Burton wrote: > > > > > Is there a way to simulate a MatSet (like VecSet) ? > > > > Simon. > > > > -- Simon Burton, B.Sc. Licensed PO Box 8066 ANU Canberra 2601 Australia Ph. 61 02 6249 6940 http://arrowtheory.com