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MPI_Type_create_f90_integer(3OpenMPI)                                  MPI_Type_create_f90_integer(3OpenMPI)



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 param-eter parameter
       eter 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  representa-tion representation
       tion  -  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 incompati-ble incompatible
       ble 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




Open MPI 1.2                                   September 2006          MPI_Type_create_f90_integer(3OpenMPI)