Re: MPI

[John W. Eaton]

On  2-Feb-2001, Alex Verstak <address@hidden> wrote:

| On Thu, 1 Feb 2001, John W. Eaton wrote:
| > On  1-Feb-2001, Alex Verstak <address@hidden> wrote:
| > | My binding is different from that of Nov 2000.  I didn't do
| > | anything fancy; just made .oct files for MPI_Send and company
| > | and added three lines to octave.cc for initialization (MPI_Init
| > | didn't work from an .oct file).
| > 
| > Can you explain why not?  What is special about MPI_Init?
| 
| It must be called with argc and argv passed to main() before
| main() processes them (see MPI standard).  MPICH's mpirun(1),
| for example, passes some startup information on the command
| line.  MPI_Init strips it off before the application can
| see it (similar to the way X libraries eat off --geometry
| switches).

Is there any reason that the argv and argc that are passed to
MPI_Init have to be the same ones that are passed to main?  Why can't
you just create whatever argv/argc pair you need and pass that to
MPI_Init?

| Also, the version of MPICH I am using does not like it when
| I return from the scope of the function that called MPI_Init.
| It just forgets that it has been initialized.

Why?  It seems like a very bad restriction that the initializatio
function for some library would *have* to be called from the one true
main().

jwe



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