ISGlobalToLocalMappingApply#

Provides the local numbering for a list of integers specified with a global numbering.

Synopsis#

#include "petscis.h"  
PetscErrorCode ISGlobalToLocalMappingApply(ISLocalToGlobalMapping mapping, ISGlobalToLocalMappingMode type, PetscInt n, const PetscInt idx[], PetscInt *nout, PetscInt idxout[])

Not Collective

Input Parameters#

  • mapping - mapping between local and global numbering

  • type - IS_GTOLM_MASK - maps global indices with no local value to -1 in the output list (i.e., mask them) IS_GTOLM_DROP - drops the indices with no local value from the output list

  • n - number of global indices to map

  • idx - global indices to map

Output Parameters#

  • nout - number of indices in output array (if type == IS_GTOLM_MASK then nout = n)

  • idxout - local index of each global index, one must pass in an array long enough to hold all the indices. You can call ISGlobalToLocalMappingApply() with idxout == NULL to determine the required length (returned in nout) and then allocate the required space and call ISGlobalToLocalMappingApply() a second time to set the values.

Notes#

Either nout or idxout may be NULL. idx and idxout may be identical.

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.

Developer Notes#

The manual page states that idx and idxout may be identical but the calling sequence declares idx as const so it cannot be the same as idxout.

See Also#

Low-level Vector Communication, ISLocalToGlobalMapping, ISLocalToGlobalMappingApply(), ISGlobalToLocalMappingApplyBlock(), ISLocalToGlobalMappingCreate(), ISLocalToGlobalMappingDestroy()

Level#

advanced

Location#

src/vec/is/utils/isltog.c

Examples#

src/vec/is/is/tutorials/ex4.c
src/vec/is/is/tutorials/ex5.c

Index of all IS routines
Table of Contents for all manual pages
Index of all manual pages