petsc object hierarchy

[Barry Smith]

On Wed, 22 Nov 2006, Yaron Kretchmer wrote:

> Thanks Matt.
> 
> And Vec sits on top of BLAS/MPI ?

  Vec and Mat both talk directly to BLAS and MPI. It is rare that
PC talks directly to MPI/Blas, usually it goes through Mat. KSP, SNES
and TS hardly ever use BLAS/MPI directly, ideally KSP, SNES and TS will not
talk to BLAS or MPI directly at all.

   Barry

PetscViewers also talk directly to MPI (not blas :-)) and are used
by all the objects.

> 
> How are Vec-Vec operators (VecAXPBY for instance) and Mat-Mat operators
> (MatMatMult) performed?
> 
> 
> Yaron
> 
> On 11/22/06, Matthew Knepley <knepley at gmail.com> wrote:
> > 
> > There is a classic slides in all the tutorials about control flow, but
> > it is really simple:
> > 
> >   - Mat uses Vec
> >   - PC uses (Mat, Vec)
> >   - KSP use (PC, Mat, Vec)
> >   - SNES uses (KSP, PC, Mat, Vec)
> >   - TS uses (SNES, KSP, PC, Mat, Vec)
> > 
> > Very linear.
> > 
> >   Matt
> > 
> > On 11/21/06, Yaron Kretchmer <yaronkretchmer at gmail.com> wrote:
> > > Hi all
> > > I'd like to understand the class/object hierarchy of Petsc (i.e. KSP
> > uses a
> > > MAT , which uses a VEC etc. etc.)- other than digging through the code,
> > how
> > > can i do this?
> > >
> > > Thanks
> > > Yaron
> > >
> > 
> > 
> > --
> > "Failure has a thousand explanations. Success doesn't need one" -- Sir
> > Alec Guiness
> > 
> > 
>