sbaij & hermitian mat-vec multiplication

[Hong Zhang]

Christos,

> Hi guys. Following up on a previous user request, I've been looking  
> at supporting hermitian mat-vec multiplication for the SBAIJ  
> implementation. I haven't played with petsc before, so please  
> forgive me for not understanding the internals. So, SBAIJ uses the  
> transpose of the upper band where access to the lower band is  
> needed. Am I right to believe that what is needed to be done is to  
> have the SBAIJ data retriever (such as MatGetValues_MPISBAIJ)  
> modified such that on sub-diagonal accesses the conjugate of the  
> original values are returned instead (possibly by updating the  
> contents of the "v" argument once filled in)?

Yes.
Be careful in parallel implementation though,

Hong