MPI_Comm_size

Determines the size of the group associated with a communicator.

Syntax

• r = MPI_Comm_size(Comm)

Input argument

• Comm - a MPI_Comm object.

Output argument

• r - an integer value: number of processes in the group of Comm.

Description

Determines the size of the group associated with a communicator.

See also

MPI_Comm_rank.

Example

mpiexec([modulepath('mpi'), '/examples/MPI_helloworld.m'], 4)

if ~MPI_Initialized()
  MPI_Init();
end
comm = MPI_Comm_object()
my_rank = MPI_Comm_rank (comm)
num_ranks = MPI_Comm_size(comm)

TAG= 1;
if (my_rank != 0)
  rankvect = 0;
  MPI_Send(rand(3,3) + my_rank, rankvect, TAG, comm);
else
  disp('MPI master receive:')
  for source = 1:num_ranks - 1
    disp(['From slave ', int2str(source)])
    message = MPI_Recv (source, TAG, comm);
    disp(message)
  end
end

if MPI_Initialized()
  MPI_Finalize();
end

History

Author

Allan CORNET