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

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`#

   void funcs(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.