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

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

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

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

.fi
.SH C++ Syntax
.nf
#include <mpi.h>
MPI::Aint MPI::Get_address(void* \fIlocation\fP)

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

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

.SH DESCRIPTION
.ft R
MPI_Get_address returns the byte address of a location in memory.
.sp
Example: Using MPI_Get_address for an array. 
.sp
.nf
EAL A(100,100) 
.fi
.br
   INTEGER I1, I2, DIFF 
.br
   CALL MPI_GET_ADDRESS(A(1,1), I1, IERROR) 
.br
   CALL MPI_GET_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
Current Fortran MPI codes will run unmodified and will port to any system. However, they may fail if addresses larger than 2^32 - 1 are used in the program. New codes should be written so that they use the new functions. This provides compatibility with C/C++ and avoids errors on 64-bit architectures. However, such newly written codes may need to be (slightly) rewritten to port to old Fortran 77 environments that do not support KIND declarations. 

.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.