MPI_Type_create_f90_integer(3)     Open MPI     MPI_Type_create_f90_integer(3)



NAME
       MPI_Type_create_f90_integer - Returns a bounded MPI integer datatype


SYNTAX
C Syntax
       #include <mpi.h>
       int MPI_Type_create_f90_integer(int r, MPI_Datatype *newtype)


Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_TYPE_CREATE_F90_INTEGER (R, NEWTYPE, IERROR)
            INTEGER   R, NEWTYPE, IERROR


C++ Syntax
       #include <mpi.h>
       static MPI::Datatype MPI::Datatype::Create_f90_integer(int r)


INPUT PARAMETER
       r         Precision, in decimal digits (integer).


OUTPUT PARAMETERS
       newtype   New data type (handle).

       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       This function provides a way to declare KIND-parameterized INTEGER MPI
       datatypes. The argument is interpreted in a similar fashion to the F90
       function SELECTED_INT_KIND: r must be a scalar integer, and represents
       the desired level of numerical precision, in decimal digits.


NOTES
       It is erroneous to supply a value for r not supported by the compiler.

       The Fortran function SELECTED_INT_KIND maps a large number of r values
       to a much smaller number of KIND parameters supported by the compiler.
       KIND parameters are not specified by the language and are not portable.
       From the point of view of the language, variables of the same base type
       and KIND parameter are equivalent, even if their KIND parameters were
       generated by different r arguments to SELECTED_INT_KIND. However, to
       help facilitate interoperability in a heterogeneous environment,
       equivalency is more strictly defined for datatypes returned by
       MPI_Type_create_f90_integer. Two MPI datatypes, each generated by this
       function, will match if and only if they have identical values for r.

       The interaction between the datatypes returned by this function and the
       external32 data representation - used by MPI_Pack_external,
       MPI_Unpack_external and many MPI_File functions - is subtle. The
       external32 representation of returned datatypes is as follows.

            if (r > 38):
                 external32 size = n/a (undefined)
            else if (r > 18):
                 external32 size = 16
            else if (r > 9):
                 external32 size = 8
            else if (r > 4):
                 external32 size = 4
            else if (r > 2):
                 external32 size = 2
            else:
                 external32 size = 1

       If the external32 representation of a datatype is undefined, so are the
       results of using that datatype in operations that require the
       external32 format. Care should be taken not to use incompatible
       datatypes indirectly, e.g., as part of another datatype or through a
       duplicated datatype, in these functions.

       If a variable is declared specifying a nondefault KIND value that was
       not obtained with SELECTED_INT_KIND (i.e., r is unknown), the only way
       to obtain a matching MPI datatype is to use the functions MPI_Sizeof
       and MPI_Type_match_size.


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.

       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.

       See the MPI man page for a full list of MPI error codes.


SEE ALSO
       MPI_Pack_external
       MPI_Sizeof
       MPI_Type_match_size
       MPI_Unpack_external
       SELECTED_INT_KIND




1.4.1                            Jan 14, 2010   MPI_Type_create_f90_integer(3)
