MPI_TYPE_HVECTOR(3)

💅 MPI_TYPE_HVECTOR(3) 💅

ok so real talk bestie, this is an Open MPI page — welcome to the strided-datatype corner of the universe 🦋

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✨ NAME ✨

MPI_Type_hvector — makes you a vector (strided) datatype where the offset is measured in bytes. but babes, heads up: this routine is deprecated in favor of MPI_Type_create_hvector 😭

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🌸 SYNTAX 🌸

🎀 C Syntax

#include <mpi.h>

int MPI_Type_hvector(int count, int blocklength, MPI_Aint stride,
     MPI_Datatype oldtype, MPI_Datatype *newtype)

🎀 Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'

MPI_TYPE_HVECTOR(COUNT, BLOCKLENGTH, STRIDE, OLDTYPE, NEWTYPE,
             IERROR)
     INTEGER COUNT, BLOCKLENGTH, STRIDE, OLDTYPE
     INTEGER NEWTYPE, IERROR

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💖 INPUT PARAMETERS 💖

• count — how many blocks you're working with. it's a nonnegative integer, no cap, no drama 🫶
• blocklength — how many elements live inside each one of those blocks. also a nonnegative integer ✨
• stride — the number of bytes between the start of each block. integer, and yes the byte thing is literally the whole point of this variant 💅
• oldtype — the old datatype, as a handle. the blueprint you're building on 🧚

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🌈 OUTPUT PARAMETERS 🌈

• newtype — your brand new datatype, as a handle. main character energy 👑
• ierror — Fortran only: the error status, as an integer 💀

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⭐ DESCRIPTION ⭐

so here's the tea 🍓 — use of this routine is deprecated as of MPI-2. like, it's not evil, it's just old news. the glow-up you want is MPI_Type_create_hvector instead. slay, moving on ✨

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😭 ERRORS 😭

almost every MPI routine hands you back an error value, no cap:

• C routines give it to you as the return result of the function 🔥
• Fortran routines tuck it into the last argument 🎀

and before that error value even reaches you, the current MPI error handler associated with the communication object (think: communicator, window, file) gets called. that's just how it goes 💅

if there's no communication object associated with the MPI call, then the call counts as being attached to MPI_COMM_SELF and it'll call that associated MPI error handler. 🦋

now, when MPI_COMM_SELF is not initialized — i.e. before MPI_Init/MPI_Init_thread, after MPI_Finalize, or when you're using the Sessions Model exclusively — the error raises the initial error handler. and you can change that initial error handler:

• by calling MPI_Comm_set_errhandler on MPI_COMM_SELF when you're using the World model 🌍
• or via the mpi_initial_errhandler CLI argument to mpiexec 💻
• or via the info key to MPI_Comm_spawn/MPI_Comm_spawn_multiple 🐣

and if no other appropriate error handler has been set? then MPI_ERRORS_RETURN gets called for MPI I/O functions, and MPI_ERRORS_ABORT gets called for all other MPI functions. periodt 💀

Open MPI ships three predefined error handlers you can use, and honestly they're iconic:

• MPI_ERRORS_ARE_FATAL — causes the program to abort all connected MPI processes. dramatic? yes. effective? also yes 😭
• MPI_ERRORS_ABORT — an error handler that can be invoked on a communicator, window, file, or session. when it's called on a communicator, it acts as if MPI_Abort was called on that communicator. if it's called on a window or file, it acts as if MPI_Abort was called on a communicator containing the group of processes in the corresponding window or file. if it's called on a session, it aborts only the local process 👑
• MPI_ERRORS_RETURN — returns an error code to the application. the chill one 🫶

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. like, fr fr, don't assume you can just keep vibing after one 💀

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_create_hvector — the non-deprecated glow-up, go here first bestie 💖
• MPI_Type_vector 🌸

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🎀 COPYRIGHT 🎀

2003-2026, The Open MPI Community

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and that's the whole page, bestie 💜 this little gem was served up on Sep 11, 2026 by the lovely humans of The Open MPI Community — go forth and stride responsibly 🦋✨🎀