MPI_Type_create_f90_integer(3) Open MPI MPI_Type_create_f90_integer(3)NAMEMPI_Type_create_f90_integer - Returns a bounded MPI integer datatype
SYNTAXC 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, equiv‐
alency is more strictly defined for datatypes returned by MPI_Type_cre‐
ate_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 exter‐
nal32 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 exter‐
nal32 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++ func‐
tions 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
1.6.4 Feb 19, 2013 MPI_Type_create_f90_integer(3)
