Petsc questions

[Nguyen, Hung V ERDC-ITL-MS]

 Barry,

Thanks for the info. I will use what we already have. How's about estimation
of matrix condition number via PETSC?

-Hung
 
-----Original Message-----
From: owner-petsc-users at mcs.anl.gov [mailto:owner-petsc-users at mcs.anl.gov] On
Behalf Of Barry Smith
Sent: Thursday, August 14, 2008 11:08 AM
To: petsc-users at mcs.anl.gov
Subject: Re: Petsc questions


    Check AO functions. They renumber between two different orderings.

But, if your code already puts everything in the new numbering, you can just
use PETSc with that new numbering and leave your ordering code as it is.

    Barry

On Aug 14, 2008, at 9:37 AM, Nguyen, Hung V ERDC-ITL-MS wrote:

>
> Hello All,
>
> I am new to PETSC. I have following questions about PETSC:
>
> 1. Do PETSC functions help to estimate/calculate a matrix condition 
> number?
> If yes, can I get the info how to do it?
>
> 2. A question about renumbering nodes: our CFD code uses ParMetis to 
> compute the original partitioning of the mesh.  The global nodes are 
> renumbered consecutively within each Parmetis partition as npetsc 
> which is a mapping vector from the original global node numbering to 
> the new numbering, see below as a test code. My question is whether 
> PETSC function helps to renumber from ParMetis partition to PETSC 
> partition or not?
>
> Thank for your help.
>
> Regards,
>
> -Hung
> -- code:
> !         Read the data.
>
>      fname = 'petsc.dat'
>      call parnam (fname)
>      open (2, file = fname, status = 'old')
>
> !         No. global nodes, local nodes, owned nodes,
> !         compressed columns, PEs.
>
>      read (2, '(5i10)') ng, nloc, nown, ncol, npes
>
>      if (noproc .ne. npes) then
>        if (myid .eq. 0) then
>          print*, 'Number of PEs from the data file does not match',
>     &      ' the number from the run command.'
>        end if
>        call PetscFinalize (ierr)
>        stop
>      end if
>
> !         Local node array containing global node numbers.
>
>      allocate (nglobal(nloc))
>
>      read (2, '(8i10)') nglobal
>
> !         Find petsc numbering scheme.
>
>      allocate (nown_all(noproc))
>      allocate (idisp(noproc))
>      allocate (npetsc(nloc))
>      allocate (nodes1(ng))
>      allocate (nodes2(ng))
>
>      call MPI_ALLGATHER (nown, 1, MPI_INTEGER, nown_all, 1,
>     &  MPI_INTEGER, PETSC_COMM_WORLD, ierr)
>
>      idisp(1) = 0
>      do i = 2, noproc
>        idisp(i) = idisp(i - 1) + nown_all(i - 1)
>      end do
>
>      call MPI_ALLGATHERV (nglobal, nown, MPI_INTEGER, nodes1,
>     &   nown_all, idisp, MPI_INTEGER, PETSC_COMM_WORLD, ierr)
>
>      do i = 1, ng
>        ii = nodes1(i)
>        nodes2(ii) = i
>      end do
>
> !         Process the local nodes for their petsc numbers.
>
>      do i = 1, nloc
>        ii = nglobal(i)
>        npetsc(i) = nodes2(ii)
>      end do
>
>