PETSc version 3.15.5
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# DMPlexComputeL2DiffVec

This function computes the cellwise L_2 difference between a function u and an FEM interpolant solution u_h, and stores it in a Vec.

### Synopsis

    #include "petscdmplex.h"
    PetscErrorCode DMPlexComputeL2DiffVec(DM dm, PetscReal time, PetscErrorCode (**funcs)(PetscInt, PetscReal, const PetscReal [], PetscInt, PetscScalar *, void *), void **ctxs, Vec X, Vec D)

Collective on dm

### Input Parameters

| dm | - The DM
| time | - The time
| funcs | - The functions to evaluate for each field component: NULL means that component does not contribute to error calculation
| ctxs | - Optional array of contexts to pass to each function, or NULL.
| X | - The coefficient vector u_h

### Output Parameter

| D | - A Vec which holds the difference ||u - u_h||_2 for each cell

### See Also

DMProjectFunction(), DMComputeL2Diff(), DMPlexComputeL2FieldDiff(), DMComputeL2GradientDiff()

### Level

developer

### Location

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