petsc-3.8.4 2018-03-24

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 - replaces global indices with no local value with -1 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 Note: 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.

Examples