/*D
   MPI_Allgatherv - Gathers data from all tasks and deliver the combined data to all tasks

Synopsis:
.vb
int MPI_Allgatherv(const void *sendbuf, int sendcount, MPI_Datatype sendtype,
                   void *recvbuf, const int recvcounts[], const int displs[],
                   MPI_Datatype recvtype, MPI_Comm comm)
.ve
.vb
int MPI_Allgatherv_c(const void *sendbuf, MPI_Count sendcount,
                     MPI_Datatype sendtype, void *recvbuf,
                     const MPI_Count recvcounts[], const MPI_Aint displs[],
                     MPI_Datatype recvtype, MPI_Comm comm)
.ve

Input Parameters:
+ sendbuf - starting address of send buffer (choice)
. sendcount - number of elements in send buffer (non-negative integer)
. sendtype - data type of send buffer elements (handle)
. recvcounts - non-negative integer array (of length group size) containing the number of elements that are received from each process (non-negative integer)
. displs - integer array (of length group size). Entry i specifies the displacement (relative to recvbuf) at which to place the incoming data from process i (integer)
. recvtype - data type of receive buffer elements (handle)
- comm - communicator (handle)

Output Parameters:
. recvbuf - address of receive buffer (choice)

Notes:
 The MPI standard (1.0 and 1.1) says that
.n
.n
 The jth block of data sent from
 each process is received by every process and placed in the jth block of the
 buffer 'recvbuf'.
.n
.n
 This is misleading; a better description is
.n
.n
 The block of data sent from the jth process is received by every
 process and placed in the jth block of the buffer 'recvbuf'.
.n
.n
 This text was suggested by Rajeev Thakur, and has been adopted as a
 clarification to the MPI standard by the MPI-Forum.

.N ThreadSafe

.N Fortran

.N Errors
.N MPI_SUCCESS
.N MPI_ERR_BUFFER
.N MPI_ERR_COMM
.N MPI_ERR_COUNT
.N MPI_ERR_TYPE
.N MPI_ERR_OTHER

D*/

