.\" -*- nroff -*-
.\" Copyright 2010 Cisco Systems, Inc.  All rights reserved.
.\" Copyright 2006-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines Corporation
.\" $COPYRIGHT$
.TH MPI_Type_match_size 3 "Sep 30, 2023" "4.1.6" "Open MPI"
.SH NAME

\fBMPI_Type_match_size\fP \- Returns an MPI datatype of a given type and size

.SH SYNTAX
.ft R

.SH C Syntax
.nf
#include <mpi.h>
int MPI_Type_match_size(int \fItypeclass\fP, int \fIsize\fP,
	MPI_Datatype *\fItype\fP)

.fi
.SH Fortran Syntax
.nf
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_TYPE_MATCH_SIZE(\fITYPECLASS, SIZE, TYPE, IERROR\fP)
	INTEGER	\fITYPECLASS, SIZE, TYPE, IERROR\fP

.fi
.SH Fortran 2008 Syntax
.nf
USE mpi_f08
MPI_Type_match_size(\fItypeclass\fP, \fIsize\fP, \fIdatatype\fP, \fIierror\fP)
	INTEGER, INTENT(IN) :: \fItypeclass\fP, \fIsize\fP
	TYPE(MPI_Datatype), INTENT(OUT) :: \fIdatatype\fP
	INTEGER, OPTIONAL, INTENT(OUT) :: \fIierror\fP

.fi
.SH C++ Syntax
.nf
#include <mpi.h>
static MPI::Datatype MPI::Match_size(int \fItypeclass\fP, int \fIsize\fP)

.fi
.SH INPUT PARAMETERS
.ft R
.TP 1i
typeclass
Generic type specifier (integer).
.ft R
.TP 1i
size
Size, in bytes, of representation (integer).

.SH OUTPUT PARAMETERS
.ft R
.TP 1i
type
Datatype with correct type and size (handle).
.ft R
.TP 1i
IERROR
Fortran only: Error status (integer).

.SH DESCRIPTION
.ft R
The function returns an MPI datatype matching a local variable of type
(\fItypeclass\fP, \fIsize\fP). The returned type is a reference
(handle) to a predefined named datatype, not a duplicate. This type
cannot be freed.
.sp
The value of \fItypeclass\fR may be set to one of MPI_TYPECLASS_REAL,
MPI_TYPECLASS_INTEGER, or MPI_TYPECLASS_COMPLEX, corresponding to the
desired datatype.
.sp
MPI_type_match_size can be used to obtain a size-specific type that
matches a Fortran numeric intrinsic type: first call MPI_Sizeof to
compute the variable size, then call MPI_Type_match_size to find a
suitable datatype. In C and C++, use the sizeof builtin instead of
MPI_Sizeof.
.sp
It is erroneous to specify a size not supported by the compiler.

.SH ERRORS
.ft R
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.
.sp
See the MPI man page for a full list of MPI error codes.

.SH SEE ALSO
.ft R
.nf
MPI_Sizeof
MPI_Type_get_extent