MPI_GROUP_RANGE_INCL(3)

💖 NAME 💖

MPI_Group_range_incl — Creates a new group from ranges of ranks in an existing group.

okay bestie, welcome to the MPI_GROUP_RANGE_INCL(3) page from Open MPI — this is literally the “make a new group out of rank ranges” routine, and it’s giving index-craft with main character energy 💅✨

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✨ SYNOPSIS ✨

C Syntax

#include <mpi.h>

int MPI_Group_range_incl(MPI_Group group, int n, int ranges[][3],
     MPI_Group *newgroup)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_GROUP_RANGE_INCL(GROUP, N, RANGES, NEWGROUP, IERROR)
     INTEGER GROUP, N, RANGES(3,*), NEWGROUP, IERROR

Fortran 2008 Syntax

USE mpi_f08
MPI_Group_range_incl(group, n, ranges, newgroup, ierror)
     TYPE(MPI_Group), INTENT(IN) :: group
     INTEGER, INTENT(IN) :: n, ranges(3,n)
     TYPE(MPI_Group), INTENT(OUT) :: newgroup
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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🌸 INPUT PARAMETERS 🌸

• group — Group (handle). 🫶
• n — Number of triplets in array ranges (integer).
• ranges — A one-dimensional array of integer triplets, of the form (first rank, last rank, stride) indicating ranks in group or processes to be included in newgroup.

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🎀 OUTPUT PARAMETERS 🎀

• newgroup — New group derived from above, in the order defined by ranges (handle).
• ierror — Fortran only: Error status (integer).

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🦋 DESCRIPTION 🦋

If ranges consist of the triplets

(first1, last1, stride1), ..., (firstn, lastn, striden)

then newgroup consists of the sequence of processes in group with ranks

                                                         last(1)-first(1)
          first(1), first(1) + stride(1),..., first(1) + ---------------- stride(1),...
                                                             stride(1)

                                                         last(n)-first(n)
          first(n), first(n) + stride(n),..., first(n) + ---------------- stride(n).
                                                             stride(n)

Each computed rank must be a valid rank in group and all computed ranks must be distinct, or else the program is erroneous. No cap, that “erroneous” part is serious. Note that we may have first(i) > last(i), and stride(i) may be negative, but cannot be zero. 🚨

The functionality of this routine is specified to be equivalent to expanding the array of ranges to an array of the included ranks and passing the resulting array of ranks and other arguments to MPI_Group_incl. A call to MPI_Group_incl is equivalent to a call to MPI_Group_range_incl with each rank i in ranks replaced by the triplet (i,i,1) in the argument ranges.

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🧚 NOTE 🧚

Heads up, bestie: this implementation does not currently check to see that the list of ranges to include are valid ranks in the group. So like… vibe check your own ranges, okay? 💀

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🔥 ERRORS 🔥

Almost all MPI routines return an error value; C routines as the return result of the function and Fortran routines in the last argument.

Before the error value is returned, the current MPI error handler associated with the communication object (e.g., communicator, window, file) is called. If no communication object is associated with the MPI call, then the call is considered attached to MPI_COMM_SELF and will call the associated MPI error handler. When MPI_COMM_SELF is not initialized (i.e., before MPI_Init/MPI_Init_thread, after MPI_Finalize, or when using the Sessions Model exclusively) the error raises the initial error handler. The initial error handler can be changed by calling MPI_Comm_set_errhandler on MPI_COMM_SELF when using the World model, or the mpi_initial_errhandler CLI argument to mpiexec or info key to MPI_Comm_spawn/MPI_Comm_spawn_multiple. If no other appropriate error handler has been set, then the MPI_ERRORS_RETURN error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is called for all other MPI functions.

Open MPI includes three predefined error handlers that can be used:

• MPI_ERRORS_ARE_FATAL — Causes the program to abort all connected MPI processes.
• MPI_ERRORS_ABORT — An error handler that can be invoked on a communicator, window, file, or session. When called on a communicator, it acts as if MPI_Abort was called on that communicator. If called on a window or file, acts as if MPI_Abort was called on a communicator containing the group of processes in the corresponding window or file. If called on a session, aborts only the local process.
• MPI_ERRORS_RETURN — Returns an error code to the application.

MPI applications can also implement their own error handlers by calling:

• MPI_Comm_create_errhandler then MPI_Comm_set_errhandler
• MPI_File_create_errhandler then MPI_File_set_errhandler
• MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init
• MPI_Win_create_errhandler then MPI_Win_set_errhandler

Note that MPI does not guarantee that an MPI program can continue past an error. 😭

See the MPI man page for a full list of MPI error codes.

See the Error Handling section of the MPI-3.1 standard for more information.

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👀 SEE ALSO 👀

• MPI_Group_incl
• MPI_Group_free

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💌 COPYRIGHT 💌

2003-2026, The Open MPI Community

💖 source/version: Open MPI · date: Sep 11, 2026 — that’s the MPI_GROUP_RANGE_INCL(3) page, bestie! Go slay those ranges! 💅🫶