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mpi_type_indexed(3openmpi) [osx man page]

MPI_Type_indexed(3OpenMPI)												MPI_Type_indexed(3OpenMPI)

MPI_Type_indexed - Creates an indexed datatype. SYNTAX
C Syntax #include <mpi.h> int MPI_Type_indexed(int count, int *array_of_blocklengths, int *array_of_displacements, MPI_Datatype oldtype, MPI_Datatype *newtype) Fortran Syntax INCLUDE 'mpif.h' MPI_TYPE_INDEXED(COUNT, ARRAY_OF_BLOCKLENGTHS, ARRAY_OF_DISPLACEMENTS, OLDTYPE, NEWTYPE, IERROR) INTEGER COUNT, ARRAY_OF_BLOCKLENGTHS(*) INTEGER ARRAY_OF_DISPLACEMENTS(*), OLDTYPE, NEWTYPE INTEGER IERROR C++ Syntax #include <mpi.h> Datatype Datatype::Create_indexed(int count, const int array_of_blocklengths[], const int array_of_displacements[]) const INPUT PARAMETERS
count Number of blocks -- also number of entries in array_of_displacements and array_of_blocklengths (nonnegative integer). array_of_blocklengths Number of elements per block (array of nonnegative integers). array_of_displacements Displacement for each block, in multiples of oldtype extent (array of integer). oldtype Old datatype (handle). OUTPUT PARAMETERS
newtype New datatype (handle). IERROR Fortran only: Error status (integer). DESCRIPTION
The function MPI_Type_indexed allows replication of an old datatype into a sequence of blocks (each block is a concatenation of the old datatype), where each block can contain a different number of copies and have a different displacement. All block displacements are multi- ples of the old data type's extent. Example: Let oldtype have type map {(double, 0), (char, 8)}, with extent 16. Let B = (3, 1) and let D = (4, 0). A call to MPI_Type_indexed(2, B, D, oldtype, newtype) returns a datatype with type map {(double, 64), (char, 72), (double, 80), (char, 88), (double, 96), (char, 104), (double, 0), (char, 8)} That is, three copies of the old type starting at displacement 4 x 16 = 64, and one copy starting at displacement 0. In general, assume that oldtype has type map {(type(0), disp(0)), ..., (type(n-1), disp(n-1))}, with extent ex. Let B be the array_of_blocklength argument and D be the array_of_displacements argument. The newly created datatype has n x S ^count-1 i = 0 B[i] entries: {(type(0), disp(0) + D[0]* ex), ..., (type(n-1), disp(n-1) + D[0]* ex), ..., (type(0), disp(0) + (D[0] + B[0]-1)* ex), ..., (type(n-1), disp(n-1) + (D[0]+ B[0]-1)* ex), ..., (type(0), disp(0) + D[count-1]* ex), ..., (type(n-1), disp(n-1) + D[count-1]* ex), ..., (type(0), disp(0) + (D[count-1] + B[count-1] -1)* ex), ..., (type(n-1), disp(n-1) + (D[count-1] + B[count-1] -1)* ex)} A call to MPI_Type_vector(count, blocklength, stride, oldtype, newtype) is equivalent to a call to MPI_Type_indexed(count, B, D, oldtype, newtype) where D[j] = j * stride, j = 0,..., count-1 and B[j] = blocklength, j = 0, .., count-1 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 ALSO
MPI_Type_create_hindexed MPI_Type_hindexed Open MPI 1.2 September 2006 MPI_Type_indexed(3OpenMPI)
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