mpi_type_get_envelope.3

MPI stands for the Message Passing Interface. Written by the MPI Forum (a large committee comprising

.\"Copyright 2006, Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines Corporation
.TH MPI_Type_get_envelope 3OpenMPI "September 2006" "Open MPI 1.2" " "
.SH NAME
\fBMPI_Type_get_envelope\fP \- Returns informaion about input arguments associated with a data type. 

.SH SYNTAX
.ft R
.SH C Syntax
.nf
#include <mpi.h>
int MPI_Type_get_envelope(MPI_Datatype \fIdatatype\fP, int *\fInum_integers\fP,
	int *\fInum_addresses\fP, int *\fInum_datatypes\fP, int *\fIcombiner\fP)

.SH Fortran Syntax 
.nf
INCLUDE 'mpif.h'
MPI_TYPE_GET_ENVELOPE(\fIDATATYPE, NUM_INTEGERS, NUM_ADDRESSES,
		NUM_DATATYPES, COMBINER, IERROR\fP)
	INTEGER	\fIDATATYPE, NUM_INTEGERS, NUM_ADDRESSES\fP
	INTEGER	\fINUM_DATATYPES, COMBINER, IERROR\fP

.SH C++ Syntax
.nf
#include <mpi.h>
void MPI::Datatype::Get_envelope(int& \fInum_integers\fP, 
	int& \fInum_addresses\fP, int& \fInum_datatypes\fP, 
	int& \fIcombiner\fP) const

.SH INPUT PARAMETER
.ft R
.TP 1i
datatype
Data type to access (handle).

.SH OUTPUT PARAMETERS
.ft R
.TP 1i
num_integers
Number of input integers used in the call constructing \fIcombiner\fP (nonnegative integer).
.TP 1i
num_addresses
Number of input addresses used in the call constructing \fIcombiner\fP (nonnegative integer).
.TP 1i
num_datatypes
Number of input data types used in the call constructing \fIcombiner\fP (nonnegative integer).
.TP 1i
combiner
Combiner (state). 
.TP 1i
IERROR
Fortran only: Error status (integer). 

.SH DESCRIPTION
.ft R
For the given data type, MPI_Type_get_envelope returns information on the number and type of input arguments used in teh 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 \fIdatatype\fP. 

.SH NOTES
.ft R
These are the values that can be returned in \fIcombiner\fP and their associated calls:
.sp
.nf
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
.fi
.sp
If \fIcombiner\fP is MPI_COMBINER_NAMED, then \fIdatatype\fP is a named predefined data type.
.sp
The actual arguments used in the creation call for a data type can be obtained from the call MPI_Type_get_contents. 

.SH 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.
.sp
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.  

.SH SEE ALSO
.ft r
MPI_Type_get_contents
.br