ISLocalToGlobalMappingCreate#

Creates a mapping between a local (0 to n) ordering and a global parallel ordering.

Synopsis#

#include "petscis.h"  
PetscErrorCode ISLocalToGlobalMappingCreate(MPI_Comm comm, PetscInt bs, PetscInt n, const PetscInt indices[], PetscCopyMode mode, ISLocalToGlobalMapping *mapping)

Not Collective, but communicator may have more than one process

Input Parameters#

  • comm - MPI communicator

  • bs - the block size

  • n - the number of local elements divided by the block size, or equivalently the number of block indices

  • indices - the global index for each local element, these do not need to be in increasing order (sorted), these values should not be scaled (i.e. multiplied) by the blocksize bs

  • mode - see PetscCopyMode

Output Parameter#

  • mapping - new mapping data structure

Notes#

There is one integer value in indices per block and it represents the actual indices bs*idx + j, where j=0,..,bs-1

For “small” problems when using ISGlobalToLocalMappingApply() and ISGlobalToLocalMappingApplyBlock(), the ISLocalToGlobalMappingType of ISLOCALTOGLOBALMAPPINGBASIC will be used; this uses more memory but is faster; this approach is not scalable for extremely large mappings.

For large problems ISLOCALTOGLOBALMAPPINGHASH is used, this is scalable. Use ISLocalToGlobalMappingSetType() or call ISLocalToGlobalMappingSetFromOptions() with the option -islocaltoglobalmapping_type <basic,hash> to control which is used.

See Also#

Low-level Vector Communication, ISLocalToGlobalMapping, ISLocalToGlobalMappingDestroy(), ISLocalToGlobalMappingCreateIS(), ISLocalToGlobalMappingSetFromOptions(), ISLOCALTOGLOBALMAPPINGBASIC, ISLOCALTOGLOBALMAPPINGHASH ISLocalToGlobalMappingSetType(), ISLocalToGlobalMappingType

Level#

advanced

Location#

src/vec/is/utils/isltog.c

Examples#

src/mat/tutorials/ex3.c
src/ksp/ksp/tutorials/ex59.c
src/vec/is/is/tutorials/ex4.c
src/vec/vec/tutorials/ex8f.F90
src/vec/vec/tutorials/ex8.c
src/ksp/ksp/tutorials/ex71.c
src/vec/is/is/tutorials/ex5.c
src/ksp/ksp/tutorials/ex85.c


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