MPI_TYPE_CREATE_RESIZED(3)

💅 MPI_TYPE_CREATE_RESIZED(3) — the Open MPI glow-up 🦋

okay bestie, so this is a page from the Open MPI manual, and it's literally about MPI_Type_create_resized, which returns a new data type with new extent and upper and lower bounds. it's giving "makeover, but for a datatype" ✨

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✨ SYNTAX ✨

🎀 C Syntax

#include <mpi.h>

int MPI_Type_create_resized(MPI_Datatype oldtype, MPI_Aint lb,
     MPI_Aint extent, MPI_Datatype *newtype)

🎀 Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_TYPE_CREATE_RESIZED(OLDTYPE, LB, EXTENT, NEWTYPE, IERROR)
     INTEGER OLDTYPE, NEWTYPE, IERROR
     INTEGER(KIND=MPI_ADDRESS_KIND)  LB, EXTENT

🎀 Fortran 2008 Syntax

USE mpi_f08
MPI_Type_create_resized(oldtype, lb, extent, newtype, ierror)
     INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) :: lb, extent
     TYPE(MPI_Datatype), INTENT(IN) :: oldtype
     TYPE(MPI_Datatype), INTENT(OUT) :: newtype
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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🌸 INPUT PARAMETERS 🌸

• oldtype — your input data type, the one you're about to glow up (handle). 🫶
• lb — the new lower bound of the data type (integer).
• extent — the new extent of the data type (integer). this is the moment, fr.

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🦋 OUTPUT PARAMETERS 🦋

• newtype — the output data type (handle). brand new, main character energy 👑
• ierror — Fortran only: error status (integer).

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💖 DESCRIPTION 💖

so MPI_Type_create_resized returns in newtype a handle to a whole new data type that's identical to oldtype, except — plot twist — the lower bound of this new data type is set to be lb, and its upper bound is set to be lb + extent. iconic behavior, no cap.

any previous lb and ub markers? erased. gone. deleted. a new pair of lower bound and upper bound markers are put in the positions indicated by the lb and extent arguments. the way that it just rewrites the boundaries 😭🔥

this lowkey affects the behavior of the data type when it's used in communication operations, with count > 1, and when it's used in the construction of new derived data types. so like, it matters. a lot. 💅

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⭐ NOTE ⭐

bestie, listen to me: use of MPI_Type_create_resized is strongly recommended over the legacy MPI-1 functions MPI_Type_extent and MPI_Type_lb. those are the old ones. we don't stan. this is the upgrade. periodt. 💀

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🙈 ERRORS 🙈

almost all MPI routines return an error value, okay? 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. that's the whole tea. 🍓

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

• MPI_ERRORS_ARE_FATAL — causes the program to abort all connected MPI processes. dramatic, but make it fatal 💀
• 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. multitasking queen 👑
• MPI_ERRORS_RETURN — returns an error code to the application. polite. respectful. 🫶

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. so like... don't count on it. 😭

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_Type_get_extent

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🧚 COPYRIGHT 🧚

2003-2026, The Open MPI Community

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okay that's the whole page, bestie, you ate that 💅✨ and just so you have the receipts: this one's from Sep 11, 2026, courtesy of the Open MPI girlies — mwah, go resize something iconic 🎀🦋💖