PETSc version 3.17.0
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# DMProjectField

This projects the given function of the input fields into the function space provided, putting the coefficients in a global vector.

### Synopsis

    #include "petscdm.h"
    #include "petscdmplex.h"
    #include "petscksp.h"
    PetscErrorCode DMProjectField(DM dm, PetscReal time, Vec U,
                                  void (**funcs)(PetscInt, PetscInt, PetscInt,
                                                 const PetscInt[], const PetscInt[], const PetscScalar[], const PetscScalar[], const PetscScalar[],
                                                 const PetscInt[], const PetscInt[], const PetscScalar[], const PetscScalar[], const PetscScalar[],
                                                 PetscReal, const PetscReal[], PetscInt, const PetscScalar[], PetscScalar[]),
                                  InsertMode mode, Vec X)

Collective on DM

### Input Parameters

| dm | - The DM
| time | - The time
| U | - The input field vector
| funcs | - The functions to evaluate, one per field
| mode | - The insertion mode for values

### Output Parameter

| X | - The output vector

### Calling sequence of func

       func(PetscInt dim, PetscInt Nf, PetscInt NfAux,

            const PetscInt uOff[], const PetscInt uOff_x[], const PetscScalar u[], const PetscScalar u_t[], const PetscScalar u_x[],

            const PetscInt aOff[], const PetscInt aOff_x[], const PetscScalar a[], const PetscScalar a_t[], const PetscScalar a_x[],

            PetscReal t, const PetscReal x[], PetscInt numConstants, const PetscScalar constants[], PetscScalar f[]);

| dim | - The spatial dimension
| Nf | - The number of input fields
| NfAux | - The number of input auxiliary fields
| uOff | - The offset of each field in u[]
| uOff_x | - The offset of each field in u_x[]
| u | - The field values at this point in space
| u_t | - The field time derivative at this point in space (or NULL)
| u_x | - The field derivatives at this point in space
| aOff | - The offset of each auxiliary field in u[]
| aOff_x | - The offset of each auxiliary field in u_x[]
| a | - The auxiliary field values at this point in space
| a_t | - The auxiliary field time derivative at this point in space (or NULL)
| a_x | - The auxiliary field derivatives at this point in space
| t | - The current time
| x | - The coordinates of this point
| numConstants | - The number of constants
| constants | - The value of each constant
| f | - The value of the function at this point in space

Note: There are three different DMs that potentially interact in this function. The output DM, dm, specifies the layout of the values calculates by funcs. The input DM, attached to U, may be different. For example, you can input the solution over the full domain, but output over a piece of the boundary, or a subdomain. You can also output a different number of fields than the input, with different discretizations. Last the auxiliary DM, attached to the auxiliary field vector, which is attached to dm, can also be different. It can have a different topology, number of fields, and discretizations.

### See Also

DMProjectFieldLocal(), DMProjectFieldLabelLocal(), DMProjectFunction(), DMComputeL2Diff()

### Level

intermediate

### Location

src/ksp/ksp/utils/dmproject.c

### Examples

src/snes/tutorials/ex12.c.html
Index of all KSP routines
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