:ref:`MPI_Neighbor_allgatherv`, :ref:`MPI_Ineighbor_allgatherv`, :ref:`MPI_Neighbor_allgatherv_init` |mdash| Gathers and distributes data from and to all neighbors. Each process may contribute a different amount of data.
#include <mpi.h>
int MPI_Neighbor_allgatherv(const void *sendbuf, int sendcount,
MPI_Datatype sendtype, void *recvbuf, const int recvcounts[],
const int displs[], MPI_Datatype recvtype, MPI_Comm comm)
int MPI_Ineighbor_allgatherv(const void *sendbuf, int sendcount,
MPI_Datatype sendtype, void *recvbuf, const int recvcounts[],
const int displs[], MPI_Datatype recvtype, MPI_Comm comm,
MPI_Request *request)
int MPI_Neighbor_allgatherv(const void *sendbuf, int sendcount,
MPI_Datatype sendtype, void *recvbuf, const int recvcounts[],
const int displs[], MPI_Datatype recvtype, MPI_Comm comm,
MPI_Info info, MPI_Request *request)USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_NEIGHBOR_ALLGATHERV(SENDBUF, SENDCOUNT, SENDTYPE, RECVBUF,
RECVCOUNT, DISPLS, RECVTYPE, COMM, IERROR)
<type> SENDBUF(*), RECVBUF(*)
INTEGER SENDCOUNT, SENDTYPE, RECVCOUNT(*),
INTEGER DISPLS(*), RECVTYPE, COMM, IERROR
MPI_INEIGHBOR_ALLGATHERV(SENDBUF, SENDCOUNT, SENDTYPE, RECVBUF,
RECVCOUNT, DISPLS, RECVTYPE, COMM, REQUEST, IERROR)
<type> SENDBUF(*), RECVBUF(*)
INTEGER SENDCOUNT, SENDTYPE, RECVCOUNT(*),
INTEGER DISPLS(*), RECVTYPE, COMM,REQUEST, IERROR
MPI_NEIGHBOR_ALLGATHERV_INIT(SENDBUF, SENDCOUNT, SENDTYPE, RECVBUF,
RECVCOUNT, DISPLS, RECVTYPE, COMM, INFO, REQUEST, IERROR)
<type> SENDBUF(*), RECVBUF(*)
INTEGER SENDCOUNT, SENDTYPE, RECVCOUNT(*),
INTEGER DISPLS(*), RECVTYPE, COMM,INFO,REQUEST, IERRORUSE mpi_f08
MPI_Neighbor_allgatherv(sendbuf, sendcount, sendtype, recvbuf, recvcounts,
displs, recvtype, comm, ierror)
TYPE(*), DIMENSION(..), INTENT(IN) :: sendbuf
TYPE(*), DIMENSION(..) :: recvbuf
INTEGER, INTENT(IN) :: sendcount, recvcounts(*), displs(*)
TYPE(MPI_Datatype), INTENT(IN) :: sendtype, recvtype
TYPE(MPI_Comm), INTENT(IN) :: comm
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
MPI_Ineighbor_allgatherv(sendbuf, sendcount, sendtype, recvbuf, recvcounts,
displs, recvtype, comm, request, ierror)
TYPE(*), DIMENSION(..), INTENT(IN), ASYNCHRONOUS :: sendbuf
TYPE(*), DIMENSION(..), ASYNCHRONOUS :: recvbuf
INTEGER, INTENT(IN) :: sendcount
INTEGER, INTENT(IN), ASYNCHRONOUS :: recvcounts(*), displs(*)
TYPE(MPI_Datatype), INTENT(IN) :: sendtype, recvtype
TYPE(MPI_Comm), INTENT(IN) :: comm
TYPE(MPI_Request), INTENT(OUT) :: request
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
MPI_Neighbor_allgatherv_init(sendbuf, sendcount, sendtype, recvbuf, recvcounts,
displs, recvtype, comm, info, request, ierror)
TYPE(*), DIMENSION(..), INTENT(IN), ASYNCHRONOUS :: sendbuf
TYPE(*), DIMENSION(..), ASYNCHRONOUS :: recvbuf
INTEGER, INTENT(IN) :: sendcount
INTEGER, INTENT(IN), ASYNCHRONOUS :: recvcounts(*), displs(*)
TYPE(MPI_Datatype), INTENT(IN) :: sendtype, recvtype
TYPE(MPI_Comm), INTENT(IN) :: comm
TYPE(MPI_Info), INTENT(IN) :: info
TYPE(MPI_Request), INTENT(OUT) :: request
INTEGER, OPTIONAL, INTENT(OUT) :: ierrorsendbuf: Starting address of send buffer (choice).sendcount: Number of elements in send buffer (integer).sendtype: Datatype of send buffer elements (handle).recvcount: Integer array (of length group size) containing the number of elements that are received from each neighbor.displs: Integer array (of length group size). Entry i specifies the displacement (relative to recvbuf) at which to place the incoming data from neighbor i.recvtype: Datatype of receive buffer elements (handle).comm: Communicator (handle).info Info (handle, persistent only).:
recvbuf: Address of receive buffer (choice).request: Request (handle, non-blocking only).ierror: Fortran only: Error status (integer).
:ref:`MPI_Neighbor_allgatherv` is similar to :ref:`MPI_Neighbor_allgather` in that all processes gather data from all neighbors, except that each process can send a different amount of data. The block of data sent from the jth neighbor is received by every neighbor and placed in the jth block of the buffer. The neighbors and buffer layout is determined by the topology of comm. recvbuf.
The type signature associated with sendcount, sendtype, at process j must be equal to the type signature associated with the corresponding entry in recvcounts on neighboring processes.
For a distributed graph topology, created with :ref:`MPI_Dist_graph_create`, the sequence of neighbors in the send and receive buffers at each process is defined as the sequence returned by :ref:`MPI_Dist_graph_neighbors` for destinations and sources, respectively. For a general graph topology, created with :ref:`MPI_Graph_create`, the order of neighbors in the send and receive buffers is defined as the sequence of neighbors as returned by :ref:`MPI_Graph_neighbors`. Note that general graph topologies should generally be replaced by the distributed graph topologies.
For a Cartesian topology, created with :ref:`MPI_Cart_create`, the sequence of
neighbors in the send and receive buffers at each process is defined by
order of the dimensions, first the neighbor in the negative direction
and then in the positive direction with displacement 1. The numbers of
sources and destinations in the communication routines are 2*ndims with
ndims defined in :ref:`MPI_Cart_create`. If a neighbor does not exist, i.e., at
the border of a Cartesian topology in the case of a non-periodic virtual
grid dimension (i.e., periods[...]==false), then this neighbor is
defined to be MPI_PROC_NULL.
If a neighbor in any of the functions is MPI_PROC_NULL, then the
neighborhood collective communication behaves like a point-to-point
communication with MPI_PROC_NULL in this direction. That is, the buffer
is still part of the sequence of neighbors but it is neither
communicated nor updated.
The MPI_IN_PLACE option for sendbuf is not meaningful for this operation.
.. seealso::
* :ref:`MPI_Neighbor_allgather`
* :ref:`MPI_Cart_create`
* :ref:`MPI_Graph_create`
* :ref:`MPI_Dist_graph_create`