Newsgroups: comp.parallel.mpi From: nabaker@blue.weeg.uiowa.edu (N. Baker) Subject: MPI_Gather questions. Summary: MPI_Gather questions Keywords: mpi, parallel, gather Organization: The University of Iowa Date: 16 Jul 97 20:49:51 GMT Message-ID: Hi -- I'm using MPI_Gather in a loop through my processes. Suppose i is my loop variable. Every process (including i) needs to send a float array (send_array) of variable length (send_count) to recv_array of known length (recv_count) on process i. send_count and recv_count vary between processes, but recv_count is the sum of the send_count's over all the processes and recv_array is set up accordingly (i.e., it's big enough). So I call MPI_Gather(&send_array, send_count, MPI_FLOAT, &recv_array, recv_count, MPI_FLOAT, i, MPI_COMM_WORLD); Sometimes MPI_Gather hangs when the i_th process gathers to itself. Once, it scrambled one of the process ranks. Every time, however, the recv_array is missing data. I've used MPI_Gather() outside of this loop without any troubles, but can't figure out what's going on this time. If anyone has any ideas (other than just using Send/Recv), I'd appreciate them. Thanks! Nathan Baker -- ------------------------------------------ Nathan Baker * nabaker@blue weeg.uiowa.edu ------------------------------------------