# ISGlobalToLocalMappingApply

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

### Synopsis

    #include "petscsys.h"
    #include "petscis.h"
    PetscErrorCode PETSCVEC_DLLEXPORT ISGlobalToLocalMappingApply(ISLocalToGlobalMapping mapping,ISGlobalToLocalMappingType 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 == PETSC_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 PETSC_NULL. idx and idxout may be identical.

This is not scalable in memory usage. Each processor requires O(Nglobal) size array to compute these.

### See Also

ISLocalToGlobalMappingApply(), ISLocalToGlobalMappingCreate(),
ISLocalToGlobalMappingDestroy()

Level:advanced
Location:src/vec/is/utils/isltog.c
Index of all IS routines
Table of Contents for all manual pages
Index of all manual pages

### Examples

src/vec/is/examples/tutorials/ex4.c.html