PETSc version 3.17.0
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# DMSetNullSpaceConstructor

Provide a callback function which constructs the nullspace for a given field when function spaces are joined or split, such as in DMCreateSubDM()

### Synopsis

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

Logically collective on DM

### Input Parameters

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

DMGetNullSpaceConstructor(), DMSetNearNullSpaceConstructor(), DMGetNearNullSpaceConstructor(), DMCreateSubDM(), DMCreateSuperDM()

### Level

intermediate

### Location

src/dm/interface/dm.c

### Examples

src/snes/tutorials/ex62.c.html
src/snes/tutorials/ex69.c.html
Index of all DM routines
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Index of all manual pages