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