petsc I/O

[Matt Funk]

Hi,

thanks for the answers first of all. I have another question though ... :)

Say, i want to print a specific element from a PETSc global vector. Is there a 
function (PetscSunchFPrintF does not do this i believe) to which i simply 
pass the file handle, communicator, the vector and the element and it writes 
the value to the file?


thanks
mat

On Wednesday 13 September 2006 17:13, Berend van Wachem wrote:
> Hi Matt,
>
> > i need to read in an input file. So to open my file i use PETSCFOpen
> > which works fine. But then my problems begin ... :)
> >
> > I guess i need to tell only the first proc in the communicator to fscan.
> > But is there a PETSC function that returns me the processor id?
> > And when i read the parameters in on the first proc i need to broadcast
> > them to the other procs. Does PETSC have anything for this?
>
> For both issues you can use standard MPI:
>
> to get the processor ID:
> ierr=MPI_Comm_rank(MPI_Comm Communicator,int *rank);
>
> to broadcast information:
> ierr=MPI_Bcast ( void *buffer, int count, MPI_Datatype datatype, int
> root,  MPI_Comm comm )
>
> If possible, I would recommend you to use the PetscViewer interface for
> your IO handling; it is very easy.
>
> Good luck,
>
> Berend.