NAME

       MPI_Type_create_f90_complex - Returns a bounded MPI complex datatype

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Type_create_f90_complex(int p, int r,
            MPI_Datatype *newtype)

Fortran Syntax

       INCLUDE 'mpif.h'
       MPI_TYPE_CREATE_F90_COMPLEX (P, R, NEWTYPE, IERROR)
            INTEGER   P, R, NEWTYPE, IERROR

C++ Syntax

       #include <mpi.h>
       static MPI::Datatype MPI::Datatype::Create_f90_complex(int p, int r)

INPUT PARAMETERS

       p         Precision, in decimal digits (integer).

       r         Decimal exponent range (integer).

OUTPUT PARAMETERS

       newtype   New data type (handle).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       This  function  provides  a  way  to declare KIND-parameterized COMPLEX MPI datatypes. The
       arguments are interpreted in a similar fashion to the F90 function SELECTED_REAL_KIND. The
       parameters  p  and r must be scalar integers. The argument p represents the required level
       of numerical precision, in  decimal  digits.  The  r  parameter  indicates  the  range  of
       exponents desired: the returned datatype will have at least one exponent between +r and -r
       (inclusive).

       Either p or r, but not both, may be omitted from calls to  SELECTED_REAL_KIND.  Similarly,
       either argument to MPI_Type_create_f90_complex may be set to MPI_UNDEFINED.

NOTES

       It is erroneous to supply values for p and r not supported by the compiler.

       The  Fortran  function  SELECTED_REAL_KIND  maps  a  large number of (p,r) pairs 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 (p,r) arguments to SELECTED_REAL_KIND. However, to
       help facilitate interoperability in  a  heterogeneous  environment,  equivalency  is  more
       strictly defined for datatypes returned by MPI_Type_create_f90_complex. Two MPI datatypes,
       each generated by this function, will match if and only if they have identical values  for
       both p and 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 (p > 33) and/or (r > 4931):
                 external32 size = n/a (undefined)
            else if (p > 15) and/or (r > 307):
                 external32 size = 32
            else if (p > 6) and/or (r > 37):
                 external32 size = 16
            else:
                 external32 size = 8

       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_REAL_KIND  (i.e.,  p and/or r are 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_REAL_KIND