/*D
   MPI_Allgather - Gathers data from all tasks and distribute the combined data to all tasks

Synopsis:
.vb
int MPI_Allgather(const void *sendbuf, int sendcount, MPI_Datatype sendtype,
                  void *recvbuf, int recvcount, MPI_Datatype recvtype,
                  MPI_Comm comm)
.ve
.vb
int MPI_Allgather_c(const void *sendbuf, MPI_Count sendcount,
                    MPI_Datatype sendtype, void *recvbuf, MPI_Count recvcount,
                    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)
. recvcount - number of elements received from any process (non-negative 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 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*/

