MPI_TYPE_VECTOR(3)

💅 MPI_TYPE_VECTOR(3) 💅

okay so bestie, welcome to Open MPI's page for MPI_Type_vector — the strided-datatype builder of your dreams. sit down, grab a strawberry drink 🍓, and let's get into it.

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✨ NAME ✨

MPI_Type_vector — creates a vector (strided) datatype. that's the whole vibe. 💫

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✨ SYNTAX ✨

🌸 C Syntax 🌸

#include <mpi.h>

int MPI_Type_vector(int count, int blocklength, int stride,
     MPI_Datatype oldtype, MPI_Datatype *newtype)

🎀 Fortran Syntax 🎀

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_TYPE_VECTOR(COUNT, BLOCKLENGTH, STRIDE, OLDTYPE, NEWTYPE,
             IERROR)
     INTEGER COUNT, BLOCKLENGTH, STRIDE, OLDTYPE
     INTEGER NEWTYPE, IERROR

🦋 Fortran 2008 Syntax 🦋

USE mpi_f08
MPI_Type_vector(count, blocklength, stride, oldtype, newtype, ierror)
     INTEGER, INTENT(IN) :: count, blocklength, stride
     TYPE(MPI_Datatype), INTENT(IN) :: oldtype
     TYPE(MPI_Datatype), INTENT(OUT) :: newtype
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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🌈 INPUT PARAMETERS 🌈

• count — how many blocks you want, bestie. nonnegative integer, no negativity allowed ✋
• blocklength — how many elements live inside each block (nonnegative integer).
• stride — how many elements sit between the start of each block (integer — this one's allowed to be spicy and go negative 😏).
• oldtype — the old datatype (handle). the glow-up starts here.

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💖 OUTPUT PARAMETERS 💖

• newtype — the brand-new datatype (handle). she's here, she's iconic 👑
• ierror — Fortran only: error status (integer).

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🔥 DESCRIPTION 🔥

MPI_Type_vector is the general constructor that lets you replicate a datatype into locations made of equally spaced blocks. it's giving "copy-paste but with intent". each block is built by concatenating the same number of copies of oldtype, and the spacing between blocks is a multiple of the extent of oldtype. math is mathing, we love to see it ✨

Example 1: assume, again, that oldtype has type map {(double, 0), (char, 8)}, with extent 16. a call to MPI_Type_vector(2, 3, 4, oldtype, newtype) will create the datatype with type map

{(double, 0), (char, 8), (double, 16), (char, 24),
(double, 32), (char, 40),
(double, 64), (char, 72),
(double, 80), (char, 88), (double, 96), (char, 104)}

that's two blocks with three copies each of the old type, with a stride of 4 elements (4 x 16 bytes) between the blocks. no cap. 💀

Example 2: a call to MPI_Type_vector(3, 1, -2, oldtype, newtype) will create the datatype

{(double, 0), (char, 8), (double, -32), (char, -24),
(double, -64), (char, -56)}

yes the displacements go negative, she's built different 🙈

in general, 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 x bl x 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 * ex),..., (type(n-1),
disp(n-1) + stride * ex), ...,
(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) * ex), ...,
(type(n-1), disp(n-1) + stride * (count -1) * ex), ...,
(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. genuinely obsessed. 🫶

a call to MPI_Type_contiguous(count, oldtype, newtype) is equivalent to a call to MPI_Type_vector(count, 1, 1, oldtype, newtype), or to a call to MPI_Type_vector(1, count, n, oldtype, newtype), n arbitrary. shortcuts, we stan. 💅

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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. so check it, bestie, don't just ignore it.

before that error value comes back, the current MPI error handler associated with the communication object (e.g., communicator, window, file) gets 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. it's giving bureaucracy but okay we move 🧚

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.
• 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. so like... don't count on it, 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_hvector
• MPI_Type_hvector

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🎀 COPYRIGHT 🎀

2003-2026, The Open MPI Community

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and that's the whole page, bestie!! ✨💖 before you close the tab: this was Open MPI, MPI_TYPE_VECTOR(3), dated Sep 11, 2026 — go forth and stride slay 💅🌈👑