MPI_Create_comm

Arguments

ranks

Vector of World ranks used to create the new communicator.

comm

The new communicator created.

Description

Create a communicator using world ranks given by the array "ranks". The communicator can be passed to MPI functions using the optional argument "comm". This function have to be called by all process.

Examples

MPI_Init();

worldRnk  = MPI_Comm_rank();
worldSize = MPI_Comm_size();

evenComm = MPI_Create_comm(0:2:(worldSize-1));
oddComm  = MPI_Create_comm(1:2:(worldSize-1));

// Comm rank / size
evenRnk  = MPI_Comm_rank(comm=evenComm);
oddRnk   = MPI_Comm_rank(comm=oddComm);
evenSize = MPI_Comm_size(comm=evenComm);
oddSize  = MPI_Comm_size(comm=oddComm);

if worldRnk == 0 then
    disp("world rank | world size | comm rank | comm size");
end

if evenRnk <> -1 then
    mprintf("even     %d    %d    %d    %d\n", worldRnk, worldSize, evenRnk, evenSize);
else
    mprintf("odd      %d    %d    %d    %d\n", worldRnk, worldSize, oddRnk, oddSize);
end

MPI_Finalize();

See also

• MPI_Recv — Recv data from a node
• MPI_Send — Send data from a node to another
• MPI_Init — Initialize the MPI environment
• MPI_Finalize — Terminate the MPI environment