MPI_TYPE_GET_ENVELOPE(3)

🌸 NAME 🌸

okay so this is the Open MPI manual page for MPI_Type_get_envelope — also known as MPI_TYPE_GET_ENVELOPE(3), bestie. It returns information about input arguments associated with a data type. 💅

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✨ SYNTAX ✨

💻 C Syntax 💻

#include <mpi.h>

int MPI_Type_get_envelope(MPI_Datatype datatype, int *num_integers,
     int *num_addresses, int *num_datatypes, int *combiner)

🧚 Fortran Syntax 🧚

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_TYPE_GET_ENVELOPE(DATATYPE, NUM_INTEGERS, NUM_ADDRESSES,
             NUM_DATATYPES, COMBINER, IERROR)
     INTEGER DATATYPE, NUM_INTEGERS, NUM_ADDRESSES
     INTEGER NUM_DATATYPES, COMBINER, IERROR

🦋 Fortran 2008 Syntax 🦋

USE mpi_f08
MPI_Type_get_envelope(datatype, num_integers, num_addresses, num_datatypes,
             combiner, ierror)
     TYPE(MPI_Datatype), INTENT(IN) :: datatype
     INTEGER, INTENT(OUT) :: num_integers, num_addresses, num_datatypes,
     combiner
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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🎀 INPUT PARAMETER 🎀

• datatype — Data type to access (handle). 👑

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💖 OUTPUT PARAMETERS 💖

• num_integers — Number of input integers used in the call constructing combiner (nonnegative integer). ✨
• num_addresses — Number of input addresses used in the call constructing combiner (nonnegative integer). 🌸
• num_datatypes — Number of input data types used in the call constructing combiner (nonnegative integer). 🦋
• combiner — Combiner (state). 💫
• ierror — Fortran only: Error status (integer). 🧚

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🌈 DESCRIPTION 🌈

For the given data type, MPI_Type_get_envelope returns information on the number and type of input arguments used in the call that created the data type. 🫶

The number-of-arguments values returned can be used to provide sufficiently large arrays in the decoding routine MPI_Type_get_contents. This call and the meaning of the returned values is described below. The combiner reflects the MPI data type constructor call that was used in creating datatype. 💅

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🔥 NOTES 🔥

These are the values that can be returned in combiner and their associated calls, no cap:

• MPI_COMBINER_NAMED — a named predefined data type
• MPI_COMBINER_DUP — MPI_Type_dup
• MPI_COMBINER_CONTIGUOUS — MPI_Type_contiguous
• MPI_COMBINER_VECTOR — MPI_Type_vector
• MPI_COMBINER_HVECTOR — MPI_Type_hvector and MPI_Type_create_hvector
• MPI_COMBINER_INDEXED — MPI_Type_indexed
• MPI_COMBINER_HINDEXED — MPI_Type_hindexed and MPI_Type_create_hindexed
• MPI_COMBINER_INDEXED_BLOCK — MPI_Type_create_indexed_block
• MPI_COMBINER_STRUCT — MPI_Type_struct and MPI_Type_create_struct
• MPI_COMBINER_SUBARRAY — MPI_Type_create_subarray
• MPI_COMBINER_DARRAY — MPI_Type_create_darray
• MPI_COMBINER_F90_REAL — MPI_Type_create_f90_real
• MPI_COMBINER_F90_COMPLEX — MPI_Type_create_f90_complex
• MPI_COMBINER_F90_INTEGER — MPI_Type_create_f90_integer
• MPI_COMBINER_RESIZED — MPI_Type_create_resized

If combiner is MPI_COMBINER_NAMED, then datatype is a named predefined data type. 👑

The actual arguments used in the creation call for a data type can be obtained from the call MPI_Type_get_contents. 🎀

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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_Type_get_contents

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💜 COPYRIGHT 💜

2003-2026, The Open MPI Community

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Source/version: Open MPI — dated Sep 11, 2026 — page MPI_TYPE_GET_ENVELOPE(3). Bye bestie, mwah 💋