#include "petscis.h" PetscErrorCode ISGlobalToLocalMappingApply(ISLocalToGlobalMapping mapping,ISGlobalToLocalMappingMode type,PetscInt n,const PetscInt idx[],PetscInt *nout,PetscInt idxout[])Not collective
| 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 |
| 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. |
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.