MPI_Type_get_envelope(3)

NAME
MPI_Type_get_envelope - Returns information about input arguments associated with a data type.

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
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

C++ Syntax
#include <mpi.h>
void MPI::Datatype::Get_envelope(int& num_integers,
	int& num_addresses, int& num_datatypes,
	int& combiner) const

INPUT PARAMETER

datatype
    Data type to access (handle).

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).

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.

NOTES
These are the values that can be returned in combiner and their associated calls:

Values                          Associated Calls
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_INTEGER    MPI_Type_hvector from Fortran
MPI_COMBINER_HVECTOR            MPI_Type_hvector from C or C++
                                  and MPI_Type_create for
                                  all languages
MPI_COMBINER_INDEXED            MPI_Type_indexed
MPI_COMBINER_HINDEXED_INTEGER   MPI_Type_hindexed from Fortran
MPI_COMBINER_HINDEXED           MPI_Type_hindexed from C or C++
                                  and MPI_Type_create_hindexed
                                  for all languages
MPI_COMBINER_INDEXED_BLOCK      MPI_Type_create_indexed_block
MPI_COMBINER_STRUCT_INTEGER     MPI_Type_struct from Fortran
MPI_COMBINER_STRUCT             MPI_Type_struct from C or C++
                                  and MPI_Type_create_struct
                                  for all languages
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.

ERRORS
Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI:Exception object.

Before the error value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

SEE ALSO
MPI_Type_get_contents