petsc-3.6.2 2015-10-02
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# DMDAComputeL2GradientDiff

This function computes the L_2 difference between the gradient of a function u and an FEM interpolant solution grad u_h.

### Synopsis

    #include "petscdmda.h"
    PetscErrorCode DMDAComputeL2GradientDiff(DM dm, PetscErrorCode (**funcs)(PetscInt, const PetscReal [], const PetscReal [], PetscInt, PetscScalar *, void *), void **ctxs, Vec X, const PetscReal n[], PetscReal *diff)

### Input Parameters

| dm | - The DM
| funcs | - The gradient functions to evaluate for each field component
| ctxs | - Optional array of contexts to pass to each coordinate function. ctxs itself may be null.
| X | - The coefficient vector u_h
| n | - The vector to project along

### Output Parameter

diff -The diff ||(grad u - grad u_h) . n||_2

### See Also

DMDAProjectFunction(), DMPlexComputeL2Diff()

Level:developer
Location: src/dm/impls/da/dalocal.c
Index of all DM routines
Table of Contents for all manual pages
Index of all manual pages