mpi_comm_size(3openmpi) [osx man page]

MPI_Comm_size(3OpenMPI) 												   MPI_Comm_size(3OpenMPI)

NAME

       MPI_Comm_size  - Returns the size of the group associated with a communicator.

SYNTAX

C Syntax
       #include <mpi.h>
       int MPI_Comm_size(MPI_Comm comm, int *size)

Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_COMM_SIZE(COMM, SIZE, IERROR)
	    INTEGER   COMM, SIZE, IERROR

C++ Syntax
       #include <mpi.h>
       int Comm::Get_size() const

INPUT PARAMETER

       comm	 Communicator (handle).

OUTPUT PARAMETERS

       size	 Number of processes in the group of comm (integer).

       IERROR	 Fortran only: Error status (integer).

DESCRIPTION

       This  function indicates the number of processes involved in a communicator. For MPI_COMM_WORLD, it indicates the total number of processes
       available. This function is equivalent to accessing the communicator's group with MPI_Comm_group, computing the size using  MPI_Group_size,
       and  then  freeing  the temporary group via MPI_Group_free. If the communicator is an intra-communicator (enables communication between two
       groups), this function returns the size of the local group.  To return the size of the remote group, use the MPI_Comm_remote_size function.

       This call is often used with MPI_Comm_rank  to  determine  the  amount  of  concurrency	available  for	a  specific  library  or  program.
       MPI_Comm_rank  indicates  the  rank  of	the  process  that  calls  it in the range from  0 . . . size-1, where size is the return value of
       MPI_Comm_size.

NOTE

       MPI_COMM_NULL is not considered a valid argument to this function.

ERRORS

       Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ func-
       tions  do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism
       will be used to throw an MPI:Exception object.

       Before the error value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job, except  for
       I/O  function  errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be
       used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

SEE ALSO

       MPI_Comm_group
       MPI_Comm_rank
       MPI_Comm_compare

Open MPI 1.2							  September 2006					   MPI_Comm_size(3OpenMPI)

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MPI_Comm_delete_attr(3OpenMPI)											    MPI_Comm_delete_attr(3OpenMPI)

NAME

       MPI_Comm_delete_attr - Deletes attribute value associated with a key.

SYNTAX

C Syntax
       #include <mpi.h>
       int MPI_Comm_delete_attr(MPI_Comm comm, int comm_keyval)

Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_Comm_delete_attr(COMM, COMM_KEYVAL, IERROR)
	    INTEGER   COMM, COMM_KEYVAL, IERROR

C++ Syntax
       #include <mpi.h>
       void MPI::Comm::Delete_attr(int comm_keyval)

INPUT
/OUTPUT PARAMETER
       comm	 Communicator from which the attribute is deleted (handle).

INPUT PARAMETER

       comm_keyval
		 Key value (integer).

OUTPUT PARAMETER

       IERROR	 Fortran only: Error status (integer).

DESCRIPTION

       MPI_Comm_delete_attr  deletes  an attribute from cache by key. This function invokes the attribute delete function delete_fn specified when
       the comm_keyval was created. The call will fail if the delete_fn function returns an error code other than MPI_SUCCESS.

       Whenever a communicator is replicated using the function MPI_Comm_dup, all callback copy functions for attributes that  are  currently  set
       are  invoked  (in  arbitrary order). Whenever a communicator is deleted using the function MPI_Comm_free, all callback delete functions for
       attributes that are currently set are invoked.

       This function is the same as MPI_Attr_delete but is needed to match the communicator-specific functions introduced in the  MPI-2  standard.
       The use of MPI_Attr_delete is deprecated.

ERRORS

       Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ func-
       tions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception  mechanism
       will be used to throw an MPI:Exception object.

       Before  the error value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job, except for
       I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN  may	be
       used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

Open MPI 1.2							  September 2006				    MPI_Comm_delete_attr(3OpenMPI)

Linux and UNIX Man Pages

mpi_comm_size(3openmpi) [osx man page]

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