[petsc-dev] question about Krylov solves, symmetric matrices, and ICC

[Paul Mullowney]

Hi,

I'm guessing this question has been asked and answered before on this 
list. Apologies for the repeat. Anyway, suppose I have a symmetric 
matrix stored as only L in a Matrix Market file. Then, I read in the L 
part with MatSetValues() and then do:

MatSetOption(A,MAT_SYMMETRIC,PETSC_TRUE);

Will PETSc then do a KSP solve (with say an ICC preconditioner) on the 
full matrix even though the upper part hasn't been explicitly 
created/inserted via MatSetValues()? The example below suggests not but 
I want to be absolutely sure.

http://www.mcs.anl.gov/petsc/petsc-current/src/ksp/ksp/examples/tutorials/ex2.c.html

Is there any way to work with just L?

-Paul