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All MPI names have an MPI_ prefix, and all characters are capitals.
Programs must not declare variables or functions with names beginning with
the prefix, MPI_. This is mandated to avoid possible name collisions.
All MPI Fortran subroutines have a return code in the last argument. A few
MPI operations are functions, which do not have the return code argument.
The return code value for successful completion is MPI_SUCCESS.
Other error
codes are implementation dependent; see
Chapter MPI Environmental Management
.
Handles are represented in Fortran as INTEGERs. Binary-valued
variables are of type LOGICAL.
Array arguments are indexed from one.
Unless explicitly stated, the MPI F77
binding is consistent with ANSI standard Fortran 77.
There are several points where this standard diverges from the
ANSI Fortran 77 standard.
These exceptions are consistent with common practice in the Fortran
community. In particular:
- MPI identifiers are limited to thirty, not six, significant characters.
- MPI identifiers may contain underscores after the first character.
- An MPI subroutine with a choice argument may be
called with different argument types.
An example is shown in Figure 1
. This violates the letter
of the Fortran standard, but such a violation is common practice. An
alternative would be to have a separate version of MPI_SEND
for each data type.
- Although not required, it is strongly suggested that named MPI
constants ( PARAMETERs)
be provided in an include file, called mpif.h. On systems
that do not support include files, the implementation should specify the
values of named constants.
- Vendors are encouraged to provide type declarations in
the mpif.h file on Fortran systems that
support user-defined types. One should
define, if possible, the type MPI_ADDRESS,
which is an INTEGER
of the size needed to hold an address in the execution environment.
On systems where type definition is not supported, it is up to the user to use
an INTEGER of the right kind to represent addresses (i.e.,
INTEGER*4 on a 32 bit machine, INTEGER*8 on a 64 bit machine, etc.).
double precision a
integer b
...
call MPI_send(a,...)
call MPI_send(b,...)
Figure 1: An example of calling a routine with mismatched formal
and actual arguments.
All MPI named constants can be used
wherever an entity declared with the PARAMETER attribute can be
used in Fortran.
There is one exception to this rule: the MPI constant
MPI_BOTTOM (section Address and extent functions
) can only be
used as a buffer argument.
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MPI-1.1 of June 12, 1995
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