MPI_Accumulate(3)

✨ MPI_Accumulate(3) ✨

okay bestie, we're in the MPI manual, and today's main character is MPI_Accumulate 💅

---

🌸 NAME 🌸

MPI_Accumulate — Accumulate data into the target process using remote memory access 🫶

---

🎀 SYNOPSIS 🎀

int MPI_Accumulate(const void *origin_addr, int origin_count,
MPI_Datatype origin_datatype, int target_rank,
MPI_Aint target_disp, int target_count,
MPI_Datatype target_datatype, MPI_Op op, MPI_Win win)

int MPI_Accumulate_c(const void *origin_addr, MPI_Count origin_count,
MPI_Datatype origin_datatype, int target_rank,
MPI_Aint target_disp, MPI_Count target_count,
MPI_Datatype target_datatype, MPI_Op op, MPI_Win win)

---

💖 INPUT PARAMETERS 💖

like, every single one, no skipping, periodt:

• origin_addr — initial address of buffer (choice)
• origin_count — number of entries in buffer (non-negative integer)
• origin_datatype — datatype of each entry (handle)
• target_rank — rank of target (non-negative integer)
• target_disp — displacement from start of window to beginning of target buffer (non-negative integer)
• target_count — number of entries in target buffer (non-negative integer)
• target_datatype — datatype of each entry in target buffer (handle)
• op — reduce operation (handle)
• win — window object (handle)

---

🦋 NOTES FOR FORTRAN 🦋

ngl Fortran has its own little vibe going on and you need to know the rules:

• 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 💀

bestie, listen, this part is lowkey important so read it fr fr:

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 ⚠️ (we do not stan). 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.

here's the gossip on each error code:

• MPI_SUCCESS — No error; MPI routine completed successfully. 🎉
• 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 — (no description, it's giving mystery 🙈)
• 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_Raccumulate

---

and that's the whole page, you ate that 💅✨ this was MPI manual page, from MPI, dated 4/10/2026 — go forth and accumulate, queen 🎀🦋💖