[petsc-users] using mpi

[Gryllida]

On Wed, 2 Oct 2013, at 13:38, Jed Brown wrote:
> Gryllida <gryllida at fastmail.fm> writes:
> 
> > I have a parallel program which reads data and makes a call to a
> > subroutine that uses petsc. It only needs to read data once. Is it
> > possible to implement that using MPI and then initialise petsc in the
> > subroutine? Or do I need to initialise petsc first (and use MPI calls
> > with PETSC_COMM_WORLD)?
> 
> We recommend only calling PetscInitialize and PetscFinalize once, so you
> may want to lift it to an initialization function.  You can call them
> inside the function, but if the function is called multiple times, the
> profiling and debugging functionality in PETSc will have to run each
> time, producing more output than you probably want when you turn those
> features on.
> 
> Regardless of where you initialize PETSc, you can use MPI_COMM_WORLD or
> any other communicator.

Thank you for your nudge toward that using MPI first is possible; I had a system-wide MPI installation but did not specify it to ./configure. Doing so resolved my problems.