Gauss elimination on Petsc matrices

[Toby Young]

Dear Petsc-dev;

Sorry to bring this up again.

I am trying to fit Dirchlet boundary conditions on a matrix and retain
a symmetric matrix after this operation and have run into some difficulty.

Let me pose my question in another way: Is there a Gaussian elimination in
the form of an LU decomposition (for example) implemented in Petsc?

It would be more useful in my case to assemble the system, apply boundary
conditions and then solve; not apply boundary conditions while assembling
the matrix as has been helpfully suggested.

Thank you for your useful comments on this up-to-now.

Best,
	Toby

-----

Toby D. Young (Adiunkt)
Department of Computational Science
Institute of Fundamental Technological Research
Polish Academy of Science
Room 206, ul. Swietokrzyska 21
00-049 Warszawa, POLAND