It appears that you need to start at the beginning to get some of the basics of MPI. This mailing isn’t a good forum to teach you everything you need to know, but there are great tutorials all over the web to help you out. One of my favorites for some of the most beginner topics is: http://mpitutorial.com Check that out and see if it helps with your problems. I’d also recommend the “Using MPI” series of books. Thanks, Wesley On Nov 29, 2014, at 10:00 PM, نازنین <[email protected]<mailto:[email protected]>> wrote: please give me more detail . you mean to compile mpich-3.0.4 with what flags? ./configure --prefix=/home/nazanin/program_install/mpich-3.0.4 make make install do u mean to add another flag to the command ? thanks nazi On Sat, Nov 29, 2014 at 8:53 AM, Junchao Zhang <[email protected]<mailto:[email protected]>> wrote: Try to compile your program with mpicc or mpicxx On Nov 29, 2014 8:15 AM, "نازنین" <[email protected]<mailto:[email protected]>> wrote: thank u for your reply .... can you please tell me what is the reason? it is my first time running a mpi .... i compiled a program with cpp which tells to use : export USE_MPI=on # distributed-memory parallelism export USE_MPIF90=on # compile with mpif90 script export which_MPI=mpich # compile with MPICH library #export which_MPI=mpich2 # compile with MPICH2 library # export which_MPI=openmpi # compile with OpenMPI library #export USE_OpenMP=on # shared-memory parallelism # export FORT=ifort export FORT=gfortran #export FORT=pgi #export USE_DEBUG= # use Fortran debugging flags export USE_LARGE=on # activate 64-bit compilation #export USE_NETCDF4=on # compile with NetCDF-4 library #export USE_PARALLEL_IO=on # Parallel I/O with Netcdf-4/HDF5 #export USE_MY_LIBS=on # use my library paths below and then it gives me a file(coawstM) and the manual tells me to run that file in this way : mpirun -np 2 ./coawstM swan_only.in<http://swan_only.in/> what will be the reason? is it because mpich was not compiled truely or the coawstM is not working for a reason? thank you On Sat, Nov 29, 2014 at 6:07 AM, Junchao Zhang <[email protected]<mailto:[email protected]>> wrote: As indicated by the message, you passed an invalid communicator to MPI_Comm_rank() in your program. --Junchao Zhang On Sat, Nov 29, 2014 at 4:32 AM, نازنین <[email protected]<mailto:[email protected]>> wrote: hi does any one know about this error : Fatal error in PMPI_Comm_rank: Invalid communicator, error stack: PMPI_Comm_rank(108): MPI_Comm_rank(comm=0x0, rank=0x7fff24a405bc) failed PMPI_Comm_rank(66).: Invalid communicator Fatal error in PMPI_Comm_rank: Invalid communicator, error stack: PMPI_Comm_rank(108): MPI_Comm_rank(comm=0x0, rank=0x7fff63e1598c) failed PMPI_Comm_rank(66).: Invalid communicator it is when i run mpich like : mpirun -np 2 ./coawstM swan_only.in<http://swan_only.in/> i don't know if this is a problem in my executable file (coawstM) or this is from mpich or any other hardware issues or anything else thank you for your help nazi _______________________________________________ discuss mailing list [email protected]<mailto:[email protected]> To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss _______________________________________________ discuss mailing list [email protected]<mailto:[email protected]> To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss _______________________________________________ discuss mailing list [email protected]<mailto:[email protected]> To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss _______________________________________________ discuss mailing list [email protected]<mailto:[email protected]> To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss _______________________________________________ discuss mailing list [email protected]<mailto:[email protected]> To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss