---
name: "MPI_Rget_accumulate_c"
section: "3"
platform: "linux"
package: "mpich-doc"
version: "4.0.2-3"
release: "Debian 12 (Bookworm)"
platforms: ["linux"]
url: "https://new.carta.tech/MPI_Rget_accumulate_c"
---

# MPI\_Rget\_accumulate\_c(3)

Perform an atomic, one-sided read-and-accumulate

## NAME

MPI\_Rget\_accumulate\_c -  Perform an atomic, one-sided read-and-accumulate

## SYNOPSIS

```
int MPI_Rget_accumulate_c(const void *origin_addr, MPI_Count origin_count,
MPI_Datatype origin_datatype, void *result_addr, MPI_Count result_count,
MPI_Datatype result_datatype, int target_rank, MPI_Aint target_disp,
MPI_Count target_count, MPI_Datatype target_datatype, MPI_Op op,
MPI_Win win, MPI_Request *request)
```

## INPUT PARAMETERS

- **origin\_addr**

  \- initial address of buffer (choice) (choice)

- **origin\_count**

  \- number of entries in origin buffer (non-negative integer) (non-negative integer)

- **origin\_datatype**

  \- datatype of each entry in origin buffer (handle) (handle)

- **result\_count**

  \- number of entries in result buffer (non-negative integer) (non-negative integer)

- **result\_datatype**

  \- datatype of entries in result buffer (handle) (handle)

- **target\_rank**

  \- rank of target (non-negative integer) (non-negative integer)

- **target\_disp**

  \- displacement from start of window to beginning of target buffer (non-negative integer) (non-negative integer)

- **target\_count**

  \- number of entries in target buffer (non-negative integer) (non-negative integer)

- **target\_datatype**

  \- datatype of each entry in target buffer (handle) (handle)

- **op**

  \- reduce operation (handle) (handle)

- **win**

  \- window object (handle) (handle)

## OUTPUT PARAMETERS

- **result\_addr**

  \- initial address of result buffer (choice) (choice)

- **request**

  \- RMA request (handle) (handle)

## NOTES

This operations is atomic with respect to other "accumulate" operations.

The get and accumulate steps are executed atomically for each basic element in the datatype (see MPI 3.0 Section 11.7 for details). The predefined operation *MPI\_REPLACE* provides fetch-and-set behavior.

The basic components of both the origin and target datatype must be the same predefined datatype (e.g., all  *MPI\_INT* or all  *MPI\_DOUBLE\_PRECISION* ).

## 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 communicators), *MPI\_File\_set\_errhandler* (for files), and  *MPI\_Win\_set\_errhandler* (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** guarantee that an MPI program can continue past an error; however, MPI implementations will attempt to continue whenever possible.

- **MPI\_SUCCESS**

  \- No error; MPI routine completed successfully.

- **MPI\_ERR\_ARG**

  \- Invalid argument.  Some argument is invalid and is not identified by a specific error class (e.g.,  *MPI\_ERR\_RANK* ).

- **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\_DISP**

  \-

- **MPI\_ERR\_RANK**

  \- Invalid source or destination rank.  Ranks must be between zero and the size of the communicator minus one; ranks in a receive ( *MPI\_Recv* ,  *MPI\_Irecv* ,  *MPI\_Sendrecv* , etc.) may also be  *MPI\_ANY\_SOURCE* .

- **MPI\_ERR\_TYPE**

  \- Invalid datatype argument.  Additionally, this error can occur if an uncommitted MPI\_Datatype (see  *MPI\_Type\_commit* ) is used in a communication call.

- **MPI\_ERR\_WIN**

  \- Invalid MPI window object

- **MPI\_ERR\_OTHER**

  \- Other error; use  *MPI\_Error\_string* to get more information about this error code.

## SEE ALSO

MPI\_Get\_accumulate MPI\_Fetch\_and\_op\