From help-octave-request at bevo dot che dot wisc dot edu Sun Feb 11 04:51:08 2001 Subject: Re: MPI From: Alex Verstak To: help-octave at bevo dot che dot wisc dot edu Date: Sun, 11 Feb 2001 05:49:19 -0500 (EST) On Sat, 3 Feb 2001, John W. Eaton wrote: > I took the time to look up the MPI standard, and here is what I found at > http://www-unix.mcs.anl.gov/mpi/mpi-standard/mpi-report-2.0/node43.htm#Node43: > So I don't think it matters whether you have the exact argv/argc that > are passed to main. MPI 2.0 is not widely supported yet. The latest and the greatest MPICH 1.2.1 crashes on MPI_Init(NULL, NULL). > (BTW, I think there is a slight error in the > standard, since an argc == NULL doesn't make sense.) It's a pointer to argc. > However, at http://www-unix.mcs.anl.gov/mpi/www/www3/MPI_Init.html I > see that > > The MPI standard does not say what a program can do before an MPI_INIT > or after an MPI_FINALIZE. In the MPICH implementation, you should do > as little as possible. In particular, avoid anything that changes the > external state of the program, such as opening files, reading standard > input or writing to standard output. > > But I suspect that this still doesn't mean that Octave must call > MPI_Init before doing anything, or that it must be done in main(), or > that it can't go in a .oct file, though you may need to call MPI_Init > before doing any other operations in your program. For that matter, MPI doesn't say that file i/o is available any time, not just before MPI_Init. Chances are, Octave won't run on machines where it matters anyway. ;-) Bottom line, I got the .oct file to work with MPICH on a Linux/Myrinet cluster and with LAM on a cluster of workstations. No changes to Octave necessary. I'll test it on a few other configurations before releasing the source (may take a few weeks). =alex ------------------------------------------------------------- Octave is freely available under the terms of the GNU GPL. Octave's home on the web: http://www.octave.org How to fund new projects: http://www.octave.org/funding.html Subscription information: http://www.octave.org/archive.html -------------------------------------------------------------