Dear All I noticed that MPI_DIMS_CREATE cannot split eg 361 into a 19 * 19 processor grid. Is that a feature? The code follows. I used MPICH-3.1.4 gcc-4.9.2 valery cat mpi_dims.f90 program test use mpi implicit none integer :: ierr, nnodes, ndims, dims(2), i call MPI_INIT( ierr ) ndims = 2 do i = 1, 200 nnodes = i**2 dims(:) = 0 call MPI_DIMS_CREATE( nnodes, ndims, dims, ierr ) if( dims(1) /= i ) write(*,*) i, dims enddo call MPI_FINALIZE(ierr) end program test mpif90 mpi_dims.f90 mpiexec -n 1 ./a.out 19 361 1 41 1681 1 43 1849 1 71 5041 1 73 5329 1 79 6241 1 83 6889 1 89 7921 1 137 18769 1 139 19321 1 149 22201 1 151 22801 1 157 24649 1 163 26569 1 167 27889 1 173 29929 1 179 32041 1 181 32761 1 _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss