MPI_TYPE_CREATE_HVECTOR(3)

✨ MPI_Type_create_hvector ✨

okay bestie, gather round, because we're in the Open MPI manual, section 3, and today's main character is MPI_Type_create_hvector — the datatype constructor that does vector vibes but measures its stride in bytes. 💅

---

🌸 NAME 🌸

MPI_Type_create_hvector — Creates a vector (strided) data type with offset in bytes.

---

🎀 SYNTAX 🎀

C Syntax

#include <mpi.h>

int MPI_Type_create_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_CREATE_HVECTOR(COUNT, BLOCKLENGTH, STRIDE, OLDTYPE,
     NEWTYPE, IERROR)

     INTEGER COUNT, BLOCKLENGTH, OLDTYPE, NEWTYPE, IERROR
     INTEGER(KIND=MPI_ADDRESS_KIND) STRIDE

Fortran 2008 Syntax

USE mpi_f08
MPI_Type_create_hvector(count, blocklength, stride, oldtype, newtype,
             ierror)
     INTEGER, INTENT(IN) :: count, blocklength
     INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) :: stride
     TYPE(MPI_Datatype), INTENT(IN) :: oldtype
     TYPE(MPI_Datatype), INTENT(OUT) :: newtype
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

---

💖 INPUT PARAMETERS 💖

• count</p> — Number of blocks (nonnegative integer). slay, but keep it ≥ 0.
• blocklength</p> — Number of elements in each block (nonnegative integer).
• stride</p> — Number of bytes between start of each block (integer). yes bestie, bytes, that's the whole h-thing here 🫶
• oldtype</p> — Old data type (handle).

---

🦋 OUTPUT PARAMETERS 🦋

• newtype — New data type (handle). this is the glow-up, the freshly-built icon 👑
• ierror — Fortran only: Error status (integer).

---

👑 DESCRIPTION 👑

MPI_Type_create_hvector creates a vector (strided) data type with offset in bytes. This routine replaces MPI_Type_hvector, which is deprecated — so like, don't text your ex, use the new one. 💀

The function MPI_Type_create_hvector is identical to MPI_Type_vector, except that stride is given in bytes, rather than in elements. The use for both types of vector constructors is illustrated in the examples in the Datatype chapter of the MPI Standard.

Assume that oldtype has type map

{(type(0), disp(0)), ..., (type(n-1), disp(n-1))}

with extent ex. Let bl be the blocklength. The newly created datatype has a type map with count * bl * n entries:

{(type(0), disp(0)), ..., (type(n-1), disp(n-1)),
(type(0), disp(0) + ex), ..., (type(n-1), disp(n-1) + ex),
..., (type(0), disp(0) + (bl -1) * ex),...,(type(n-1),
disp(n-1) + (bl -1) * ex), (type(0), disp(0) + stride),
...,(type(n-1), disp(n-1) + stride), ..., (type(0),
disp(0) + stride + (bl - 1) * ex), ..., (type(n-1),
disp(n-1) + stride + (bl -1) * ex), ..., (type(0),
disp(0) + stride * (count -1)), ...,(type(n-1),
disp(n-1) + stride * (count -1)), ..., (type(0),
disp(0) + stride * (count -1) + (bl -1) * ex), ...,
(type(n-1), disp(n-1) + stride * (count -1) + (bl -1) * ex)}

like… look at her go. that type map is doing the most and I respect it. 🌈

---

😭 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. it's giving "we're ending this group chat" 💀
• 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

ngl, red flag: note that MPI does not guarantee that an MPI program can continue past an error. so don't be out here assuming you get a second chance, bestie. 🙈

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.

See also:

• MPI_Type_create_hindexed
• MPI_Type_vector

---

🎀 Copyright 🎀

2003-2026, The Open MPI Community

---

okay that's the whole page, periodt. 💖 this was brought to you by Open MPI, dated Sep 10, 2026 — the MPI_TYPE_CREATE_HVECTOR(3) bestie that put the h in hvector and the slay in stride. go build something iconic with it, my love 🦋✨