Basic HTML version of Foils prepared 10 Oct 1995

Foil 34 Derived Datatype Basics

From Fox Presentation Fall 1995 CPS615 Basic Simulation Track for Computational Science -- Fall Semester 95. by Geoffrey C. Fox


1 Derived Datatypes should be declared integer in Fortran and MPI_Datatype in C
2 Generally have form { (type0,disp0), (type1,disp1) ... (type(n-1),disp(n-1)) } with list of primitive data types typei and displacements (from start of buffer) dispi
3 call MPI_TYPE_CONTIGUOUS (count, oldtype, newtype, ierr)
  • creates a new datatype newtype made up of count repetitions of old datatype oldtype
4 one must use call MPI_TYPE_COMMIT(derivedtype,ierr)
5 before one can use the type derivedtype in a communication call
6 call MPI_TYPE_FREE(derivedtype,ierr) frees up space used by this derived type

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© on Tue Oct 7 1997