PETSc version 3.17.0
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# DMPlexSetAnchors

Set the layout of the local anchor (point-to-point) constraints. Unlike boundary conditions, when a point's degrees of freedom in a section are constrained to an outside value, the anchor constraints set a point's degrees of freedom to be a linear combination of other points' degrees of freedom.

### Synopsis

    #include "petscdmplex.h"
    PetscErrorCode DMPlexSetAnchors(DM dm, PetscSection anchorSection, IS anchorIS)

After specifying the layout of constraints with DMPlexSetAnchors(), one specifies the constraints by calling DMGetDefaultConstraints() and filling in the entries in the constraint matrix.

collective on dm

### Input Parameters

| dm | - The DMPlex object
| anchorSection | - The section that describes the mapping from constrained points to the anchor points listed in anchorIS. Must have a local communicator (PETSC_COMM_SELF or derivative).
| anchorIS | - The list of all anchor points. Must have a local communicator (PETSC_COMM_SELF or derivative).

The reference counts of anchorSection and anchorIS are incremented.

### See Also

DMPlexGetAnchors(), DMGetDefaultConstraints(), DMSetDefaultConstraints()

### Level

intermediate

### Location

src/dm/impls/plex/plex.c
Index of all DMPLEX routines
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Index of all manual pages