xenial (3) MPI_Type_struct.openmpi.3.gz

NAME

       MPI_Type_struct - Creates a struct data type -- use of this routine is deprecated.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Type_struct(int count, int *array_of_blocklengths,
            MPI_Aint *array_of_displacements, MPI_Datatype *array_of_types,
            MPI_Datatype *newtype)

Fortran Syntax

       INCLUDE 'mpif.h'
       MPI_TYPE_STRUCT(COUNT, ARRAY_OF_BLOCKLENGTHS,
                 ARRAY_OF_DISPLACEMENTS, ARRAY_OF_TYPES,
                 NEWTYPE, IERROR)
            INTEGER   COUNT, ARRAY_OF_BLOCKLENGTHS(*)
            INTEGER   ARRAY_OF_DISPLACEMENTS(*)
            INTEGER   ARRAY_OF_TYPES(*), NEWTYPE, IERROR

INPUT PARAMETERS

       count     Number   of   blocks   (integer)    also   number   of   entries   in   arrays  array_of_types,
                 array_of_displacements, and array_of_blocklengths.

       array_of_blocklengths
                 Number of elements in each block (array).

       array_of_displacements
                 Byte displacement of each block (array).

       array_of_types
                 Type of elements in each block (array of handles to datatype objects).

OUTPUT PARAMETERS

       newtype   New datatype (handle).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       Note that use of this routine is deprecated as of MPI-2. Use MPI_Type_create_struct instead.

       This deprecated routine is not available in C++.

       MPI_Type_struct is the most general type constructor. It further generalizes MPI_Type_hindexed in that it
       allows each block to consist of replications of different datatypes.

       Example: Let type1 have type map

           {(double, 0), (char, 8)}

       with  extent 16. Let B = (2, 1, 3), D = (0, 16, 26), and T = (MPI_FLOAT, type1, MPI_CHAR). Then a call to
       MPI_Type_struct(3, B, D, T, newtype) returns a datatype with type map

           {(float, 0), (float,4), (double, 16), (char, 24),
           (char, 26), (char, 27), (char, 28)}

       That is, two copies of MPI_FLOAT starting at 0, followed by one copy of type1 starting at 16, followed by
       three copies of MPI_CHAR, starting at 26. (We assume that a float occupies 4 bytes.)

       For more information, see section 3.12.1 of the MPI-1.1 Standard.

NOTES

       If  an  upperbound  is  set  explicitly by using the MPI datatype MPI_UB, the corresponding index must be
       positive.

       The MPI-1 Standard originally made vague statements about padding and alignment;  this  was  intended  to
       allow the simple definition of structures that could be sent with a count greater than one. For example,
           struct {int a; char b;} foo;
       may have
           sizeof(foo) = sizeof(int) + sizeof(char);
       defining  the extent of a datatype as including an epsilon, which would have allowed an implementation to
       make the extent an MPI datatype for this structure  equal  to  2*sizeof(int).  However,  since  different
       systems  might define different paddings, a clarification to the standard made epsilon zero. Thus, if you
       define a structure datatype and wish to send or receive multiple items, you should explicitly include  an
       MPI_UB  entry  as  the last member of the structure.  For example, the following code can be used for the
       structure foo:

           blen[0] = 1; indices[0] = 0; oldtypes[0] = MPI_INT;
           blen[1] = 1; indices[1] = &foo.b - &foo; oldtypes[1] = MPI_CHAR;
           blen[2] = 1; indices[2] = sizeof(foo); oldtypes[2] = MPI_UB;
           MPI_Type_struct( 3, blen, indices, oldtypes, &newtype );

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 ALSO

       MPI_Type_create_struct
       MPI_Type_create_hindexed