PETSc version 3.17.0
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# DMGetNullSpaceConstructor

Return the callback function which constructs the nullspace for a given field, or NULL

### Synopsis

    #include "petscdm.h"
    #include "petscdmlabel.h"
    #include "petscds.h"
    PetscErrorCode DMGetNullSpaceConstructor(DM dm, PetscInt field, PetscErrorCode (**nullsp)(DM, PetscInt, PetscInt, MatNullSpace *))

Not collective

### Input Parameters

| dm | - The DM
| field | - The field number for the nullspace

### Output Parameter

| nullsp | - A callback to create the nullspace

### Calling sequence of nullsp

        PetscErrorCode nullsp(DM dm, PetscInt origField, PetscInt field, MatNullSpace *nullSpace)

| dm | - The present DM
| origField | - The field number given above, in the original DM
| field | - The field number in dm
| nullSpace | - The nullspace for the given field

This function is currently not available from Fortran.

### See Also

DMSetNullSpaceConstructor(), DMSetNearNullSpaceConstructor(), DMGetNearNullSpaceConstructor(), DMCreateSubDM(), DMCreateSuperDM()

### Level

intermediate

### Location

src/dm/interface/dm.c
Index of all DM routines
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Index of all manual pages