99. Example using MPI_ALLGATHER


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The example in this section uses intracommunicators.
Example The all-gather version of Example Examples using MPI_GATHER, MPI_GATHERV . Using MPI_ALLGATHER, we will gather 100 ints from every process in the group to every process.


    MPI_Comm comm; 
    int gsize,sendarray[100]; 
    int *rbuf; 
    ... 
    MPI_Comm_size( comm, &gsize); 
    rbuf = (int *)malloc(gsize*100*sizeof(int)); 
    MPI_Allgather( sendarray, 100, MPI_INT, rbuf, 100, MPI_INT, comm); 
After the call, every process has the group-wide concatenation of the sets of data.



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