openmpi/ompi/mpi/man/man3/MPI_Address.3in

.\"Copyright 2010 Cisco Systems, Inc.  All rights reserved.
.\"Copyright 2006-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines Corporation
.TH MPI_Address 3 "#OMPI_DATE#" "#PACKAGE_VERSION#" "#PACKAGE_NAME#"
.SH NAME
\fBMPI_Address\fP \- Gets the address of a location in memory -- use of this routine is deprecated.

.SH SYNTAX
.ft R
.SH C Syntax
.nf
#include <mpi.h> 
int MPI_Address(void *\fIlocation\fP, MPI_Aint\fP *address\fP)

.SH Fortran Syntax
.nf
INCLUDE 'mpif.h'
MPI_ADDRESS(\fILOCATION\fP,\fI ADDRESS\fP,\fI IERROR\fP)		
	<type>	\fILOCATION\fP (*) 		
	INTEGER	\fIADDRESS\fP,\fI IERROR\fP


.SH INPUT PARAMETER
.ft R
.TP 1i
location
Location in caller memory (choice).

.SH OUTPUT PARAMETERS
.ft R
.TP 1i
address
Address of location (integer).
.ft R
.TP 1i
IERROR
Fortran only: Error status (integer). 

.SH DESCRIPTION
.ft R
Note that use of this routine is \fIdeprecated\fP as of MPI-2. Please use MPI_Get_address instead. 
.sp
This deprecated routine is not available in C++. 
.sp
The address of a location in memory can be found by invoking this function. Returns the (byte) address of location.
.sp
Example: Using MPI_Address for an array. 
.sp
.nf
REAL A(100,100) 
.br
   INTEGER I1, I2, DIFF 
.br
   CALL MPI_ADDRESS(A(1,1), I1, IERROR) 
.br
   CALL MPI_ADDRESS(A(10,10), I2, IERROR) 
.br
   DIFF = I2 - I1 
.br
! The value of DIFF is 909*sizeofreal; the values of I1 and I2 are 
.br
! implementation dependent. 
.fi

.SH NOTES
.ft R
This routine is provided for both Fortran and C programmers and may be useful when writing portable code. In the current release, the address returned by this routine will be the same as that produced by the C & operator.
.sp
C users may be tempted to avoid using
MPI_Address and rely on the availability of the address operator &.
Note, however, that & cast-expression is a pointer, not an address.
ANSI C does not require that the value of a pointer (or the pointer
cast to int) be the absolute address of the object pointed at although 
this is commonly the case. Furthermore, referencing may not have a unique
definition on machines with a segmented address space. The use of
MPI_Address to "reference" C variables guarantees portability to
such machines as well.

.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
MPI_Get_address
.br