MPI_ALLGATHER( sendbuf, sendcount, sendtype, recvbuf,
recvcount, recvtype, comm)
int MPI_Allgather(void* sendbuf, int sendcount, MPI_Datatype sendtype, void* recvbuf, int recvcount, MPI_Datatype recvtype, MPI_Comm comm)
MPI_ALLGATHER(SENDBUF, SENDCOUNT, SENDTYPE, RECVBUF, RECVCOUNT, RECVTYPE, COMM, IERROR)
<type> SENDBUF(*), RECVBUF(*)
INTEGER SENDCOUNT, SENDTYPE, RECVCOUNT, RECVTYPE, COMM, IERROR
MPI_ALLGATHER can be thought of as MPI_GATHER, but
where all processes receive the result, instead of just the root.
The jth block of data sent from each process is received
by every process and placed in the jth block of the
buffer recvbuf.
Enhancement/Correction in the MPI-1.2 Standard:
The type signature associated with sendcount, sendtype, at a process must be equal to the type signature associated with recvcount, recvtype at any other process.
The outcome of a call to MPI_ALLGATHER(...) is as if all processes executed n calls to
MPI_GATHER(sendbuf,sendcount,sendtype,recvbuf,recvcount, recvtype,root,comm),for root = 0 , ..., n-1. The rules for correct usage of MPI_ALLGATHER are easily found from the corresponding rules for MPI_GATHER.
MPI_ALLGATHERV( sendbuf, sendcount, sendtype, recvbuf,
recvcounts, displs, recvtype, comm)
int MPI_Allgatherv(void* sendbuf, int sendcount, MPI_Datatype sendtype, void* recvbuf, int *recvcounts, int *displs, MPI_Datatype recvtype, MPI_Comm comm)
MPI_ALLGATHERV(SENDBUF, SENDCOUNT, SENDTYPE, RECVBUF, RECVCOUNTS, DISPLS, RECVTYPE, COMM, IERROR)
<type> SENDBUF(*), RECVBUF(*)
INTEGER SENDCOUNT, SENDTYPE, RECVCOUNTS(*), DISPLS(*), RECVTYPE, COMM, IERROR
MPI_ALLGATHERV can be thought of as MPI_GATHERV, but
where all processes receive the result, instead of just the root.
The jth block of data sent from each process is received
by every process and placed in the jth block of the
buffer recvbuf. These blocks need not all be the same size.
Enhancement/Correction in the MPI-1.2 Standard:
The type signature associated with sendcount, sendtype, at process j must be equal to the type signature associated with recvcounts[j], recvtype at any other process.
The outcome is as if all processes executed calls to
MPI_GATHERV(sendbuf,sendcount,sendtype,recvbuf,recvcounts,displs, recvtype,root,comm),for root = 0 , ..., n-1. The rules for correct usage of MPI_ALLGATHERV are easily found from the corresponding rules for MPI_GATHERV.