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MPI_Allgatherv(3)		      MPI		     MPI_Allgatherv(3)

NAME
       MPI_Allgatherv  -  Gathers data from all	tasks and deliver the combined
       data to all tasks

SYNOPSIS
       int MPI_Allgatherv(MPICH2_CONST void *sendbuf, int sendcount, MPI_Datatype sendtype,
			  void *recvbuf, MPICH2_CONST int *recvcounts, MPICH2_CONST int	*displs,
			  MPI_Datatype recvtype, MPI_Comm comm)

INPUT PARAMETERS
       sendbuf
	      -	starting address of send buffer	(choice)
       sendcount
	      -	number of elements in send buffer (integer)
       sendtype
	      -	data type of send buffer elements (handle)
       recvcounts
	      -	integer	array (of length group size) containing	the number  of
	      elements that are	to be received from each process
       displs -	 integer  array	 (of length group size). Entry i specifies the
	      displacement (relative to	recvbuf	) at which to place the	incom-
	      ing data from process i

       recvtype
	      -	data type of receive buffer elements (handle)
       comm   -	communicator (handle)

OUTPUT PARAMETER
       recvbuf
	      -	address	of receive buffer (choice)

NOTES
       The MPI standard	(1.0 and 1.1) says that

       The  jth	 block	of  data  sent	from each process is received by every
       process and placed in the jth block of the buffer recvbuf .

       This is misleading; a better description	is

       The block of data sent from  the	 jth  process  is  received  by	 every
       process and placed in the jth block of the buffer recvbuf .

       This  text  was	suggested  by Rajeev Thakur, and has been adopted as a
       clarification to	the MPI	standard by the	MPI-Forum.

THREAD AND INTERRUPT SAFETY
       This routine is thread-safe.  This  means  that	this  routine  may  be
       safely  used by multiple	threads	without	the need for any user-provided
       thread locks.  However, the routine is not interrupt safe.   Typically,
       this  is	due to the use of memory allocation routines such as malloc or
       other non-MPICH runtime routines	that  are  themselves  not  interrupt-
       safe.

NOTES FOR FORTRAN
       All  MPI	routines in Fortran (except for	MPI_WTIME and MPI_WTICK	) have
       an additional argument ierr at the end of the argument list.   ierr  is
       an  integer and has the same meaning as the return value	of the routine
       in C.  In Fortran, MPI routines are subroutines,	and are	 invoked  with
       the call	statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm )	are of type INTEGER in
       Fortran.

ERRORS
       All MPI routines	(except	MPI_Wtime and  MPI_Wtick  )  return  an	 error
       value;  C routines as the value of the function and Fortran routines in
       the last	argument.  Before the value is returned, the current MPI error
       handler	is called.  By default,	this error handler aborts the MPI job.
       The error handler may be	changed	with MPI_Comm_set_errhandler (for com-
       municators),  MPI_File_set_errhandler  (for files), and MPI_Win_set_er-
       rhandler	(for RMA windows).  The	MPI-1 routine  MPI_Errhandler_set  may
       be  used	 but  its  use	is  deprecated.	  The predefined error handler
       MPI_ERRORS_RETURN may be	used to	cause error  values  to	 be  returned.
       Note  that MPI does not guarentee that an MPI program can continue past
       an error; however, MPI implementations will attempt to  continue	 when-
       ever possible.

       MPI_ERR_BUFFER
	      -	 Invalid  buffer  pointer.  Usually a null buffer where	one is
	      not valid.
       MPI_ERR_COUNT
	      -	Invalid	count argument.	 Count arguments must be non-negative;
	      a	count of zero is often valid.
       MPI_ERR_TYPE
	      -	Invalid	datatype argument.  May	be an uncommitted MPI_Datatype
	      (see MPI_Type_commit ).

LOCATION
       src/mpi/coll/allgatherv.c

				   9/20/2012		     MPI_Allgatherv(3)

NAME | SYNOPSIS | INPUT PARAMETERS | OUTPUT PARAMETER | NOTES | THREAD AND INTERRUPT SAFETY | NOTES FOR FORTRAN | ERRORS | LOCATION

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