MPI_Accumulate - Accumulates data into a window
#include <mpi.h> int MPI_Accumulate(void *orgaddr, int orgcnt, MPI_Datatype orgtype, int rank,
MPI_Aint targdisp, int targcnt, MPI_Datatype targtype,
MPI_Op op, MPI_Win win)
- - initial address of buffer (choice)
- - number of entries in buffer (nonnegative integer)
- - datatype of each buffer entry (handle)
- - rank of target (nonnegative integer)
- - displacement from start of window to beginning of target buffer (nonnegative integer)
- - datatype of each entry in target buffer (handle)
- - reduce operation (handle)
- - window object (handle)
MPI_PUT is a special case of MPI_ACCUMULATE, with the operation MPI_REPLACE. Note, however, that MPI_PUT and MPI_ACCUMULATE have different constraints on concurrent updates. ( End of advice to users.)
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.
If an error occurs in an MPI function, the current MPI error handler is called to handle it. By default, this error handler aborts the MPI job. The error handler may be changed with MPI_Errhandler_set ; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned (in C and Fortran; this error handler is less useful in with the C++ MPI bindings. The predefined error handler MPI::ERRORS_THROW_EXCEPTIONS should be used in C++ if the error value needs to be recovered). Note that MPI does not guarantee that an MPI program can continue past an error.
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. The C++ bindings for MPI do not return error values; instead, error values are communicated by throwing exceptions of type MPI::Exception (but not by default). Exceptions are only thrown if the error value is not MPI::SUCCESS .
Note that if the MPI::ERRORS_RETURN handler is set in C++, while MPI functions will return upon an error, there will be no way to recover what the actual error value was.
- - No error; MPI routine completed successfully.
- - Invalid window. A common error is to use a null window in a call.
- - Invalid datatype argument. May be an uncommitted MPI_Datatype (see MPI_Type_commit ).
- - This error indicates than an operation has been attempted on a "closed" window. Certain one-sided operations can only be performed on windows whose epoch has been started with MPI_Win_start.
- - An internal error has been detected. This is fatal. Please send a bug report to the LAM mailing list (see http://www.lam-mpi.org/contact.php ).
- - Type not supported for this operation. This typically applies to either reduction operations (for which only a limited combination of datatypes and operations are defined, see MPI-1, section 4.9.2) or one-sided operations where the actions on specific datatpyes have not been implemented yet.
For more information, please see the official MPI Forum web site, which contains the text of both the MPI-1 and MPI-2 standards. These documents contain detailed information about each MPI function (most of which is not duplicated in these man pages).