const Quadrature<dim-1> &quadrature) const;
/**
- * To be written.
+ * Compute information about the shape functions on the cell denoted
+ * by the first argument. Derived classes will have to implement this
+ * function based on the kind of element they represent. It is called
+ * by FEValues::reinit().
+ *
+ * Conceptually, this function evaluates shape functions and their
+ * derivatives at the quadrature points represented by the mapped
+ * locations of those described by the quadrature argument to this
+ * function. In many cases, computing derivatives of shape functions
+ * (and in some cases also computing values of shape functions)
+ * requires making use of the mapping from the reference to the real
+ * cell; this information can either be taken from the @p mapping_data
+ * object that has been filled for the current cell before this
+ * function is called, or by calling the member functions of a
+ * Mapping object with the @p mapping_internal object that also
+ * corresponds to the current cell.
+ *
+ * The information computed by this function is used to fill the various
+ * member variables of the output argument of this function. Which of
+ * the member variables of that structure should be filled is determined
+ * by the update flags stored in the
+ * FiniteElement::InternalDataBase::update_each field of the object
+ * passed to this function. These flags are typically set by
+ * FiniteElement::get_data(), FiniteElement::get_face_date() and
+ * FiniteElement::get_subface_data() (or, more specifically, implementations
+ * of these functions in derived classes).
*
* An extensive discussion of the interaction between this function and
* FEValues can be found in the @ref FE_vs_Mapping_vs_FEValues documentation
* module.
+ *
+ * @param[in] cell The cell of the triangulation for which this function
+ * is to compute a mapping from the reference cell to.
+ * @param[in] cell_similarity Whether or not the cell given as first
+ * argument is simply a translation, rotation, etc of the cell for
+ * which this function was called the most recent time. This
+ * information is computed simply by matching the vertices (as stored
+ * by the Triangulation) between the previous and the current cell.
+ * The value passed here may be modified by implementations of
+ * this function and should then be returned (see the discussion of the
+ * return value of this function).
+ * @param[in] quadrature A reference to the quadrature formula in use
+ * for the current evaluation. This quadrature object is the same
+ * as the one used when creating the @p internal_data object. The
+ * current object is then responsible for evaluating shape functions
+ * at the mapped locations of the quadrature points represented by
+ * this object.
+ * @param[in] mapping A reference to the mapping object used to map
+ * from the reference cell to the current cell. This object was used
+ * to compute the information in the @p mapping_data object before the
+ * current function was called. It is also the mapping object that
+ * created the @p mapping_internal object via Mapping::get_data().
+ * You will need the reference to this mapping object most often
+ * to call Mapping::transform() to transform gradients and
+ * higher derivatives from the reference to the current cell.
+ * @param[in] mapping_internal An object specific to the mapping
+ * object. What the mapping chooses to store in there is of no
+ * relevance to the current function, but you may have to pass
+ * a reference to this object to certain functions of the
+ * Mapping class (e.g., Mapping::transform()) if you need to
+ * call them from the current function.
+ * @param[in] mapping_data The output object into which the
+ * Mapping::fill_fe_values() function wrote the mapping information
+ * corresponding to the current cell. This includes, for example,
+ * Jacobians of the mapping that may be of relevance to the
+ * current function, as well as other information that FEValues::reinit()
+ * requested from the mapping.
+ * @param[in] fe_internal A reference to an object previously
+ * created by get_data() and that may be used to store information
+ * the mapping can compute once on the reference cell. See the
+ * documentation of the FiniteElement::InternalDataBase class for an
+ * extensive description of the purpose of these objects.
+ * @param[out] output_data A reference to an object whose member
+ * variables should be computed. Not all of the members of this
+ * argument need to be filled; which ones need to be filled is
+ * determined by the update flags stored inside the
+ * @p fe_internal object.
+ *
+ * @note FEValues ensures that this function is always called with
+ * the same pair of @p fe_internal and @output_data objects. In
+ * other words, if an implementation of this function knows that it
+ * has written a piece of data into the output argument in a previous
+ * call, then there is no need to copy it there again in a later
+ * call if the implementation knows that this is the same value.
*/
virtual
void
const InternalDataBase &fe_internal,
dealii::internal::FEValues::FiniteElementRelatedData<dim, spacedim> &output_data) const = 0;
+ /**
+ * This function is the equivalent to FiniteElement::fill_fe_values(),
+ * but for faces of cells. See there for an extensive discussion
+ * of its purpose. It is called by FEFaceValues::reinit().
+ *
+ * @param[in] cell The cell of the triangulation for which this function
+ * is to compute a mapping from the reference cell to.
+ * @param[in] face_no The number of the face we are currently considering,
+ * indexed among the faces of the cell specified by the previous argument.
+ * @param[in] quadrature A reference to the quadrature formula in use
+ * for the current evaluation. This quadrature object is the same
+ * as the one used when creating the @p internal_data object. The
+ * current object is then responsible for evaluating shape functions
+ * at the mapped locations of the quadrature points represented by
+ * this object.
+ * @param[in] mapping A reference to the mapping object used to map
+ * from the reference cell to the current cell. This object was used
+ * to compute the information in the @p mapping_data object before the
+ * current function was called. It is also the mapping object that
+ * created the @p mapping_internal object via Mapping::get_data().
+ * You will need the reference to this mapping object most often
+ * to call Mapping::transform() to transform gradients and
+ * higher derivatives from the reference to the current cell.
+ * @param[in] mapping_internal An object specific to the mapping
+ * object. What the mapping chooses to store in there is of no
+ * relevance to the current function, but you may have to pass
+ * a reference to this object to certain functions of the
+ * Mapping class (e.g., Mapping::transform()) if you need to
+ * call them from the current function.
+ * @param[in] mapping_data The output object into which the
+ * Mapping::fill_fe_values() function wrote the mapping information
+ * corresponding to the current cell. This includes, for example,
+ * Jacobians of the mapping that may be of relevance to the
+ * current function, as well as other information that FEValues::reinit()
+ * requested from the mapping.
+ * @param[in] fe_internal A reference to an object previously
+ * created by get_data() and that may be used to store information
+ * the mapping can compute once on the reference cell. See the
+ * documentation of the FiniteElement::InternalDataBase class for an
+ * extensive description of the purpose of these objects.
+ * @param[out] output_data A reference to an object whose member
+ * variables should be computed. Not all of the members of this
+ * argument need to be filled; which ones need to be filled is
+ * determined by the update flags stored inside the
+ * @p fe_internal object.
+ */
virtual
void
fill_fe_face_values (const typename Triangulation<dim,spacedim>::cell_iterator &cell,
const InternalDataBase &fe_internal,
dealii::internal::FEValues::FiniteElementRelatedData<dim, spacedim> &output_data) const = 0;
+ /**
+ * This function is the equivalent to FiniteElement::fill_fe_values(),
+ * but for the children of faces of cells. See there for an extensive
+ * discussion of its purpose. It is called by FESubfaceValues::reinit().
+ *
+ * @param[in] cell The cell of the triangulation for which this function
+ * is to compute a mapping from the reference cell to.
+ * @param[in] face_no The number of the face we are currently considering,
+ * indexed among the faces of the cell specified by the previous argument.
+ * @param[in] sub_no The number of the subface, i.e., the number of the child
+ * of a face, that we are currently considering,
+ * indexed among the children of the face specified by the previous
+ * argument.
+ * @param[in] quadrature A reference to the quadrature formula in use
+ * for the current evaluation. This quadrature object is the same
+ * as the one used when creating the @p internal_data object. The
+ * current object is then responsible for evaluating shape functions
+ * at the mapped locations of the quadrature points represented by
+ * this object.
+ * @param[in] mapping A reference to the mapping object used to map
+ * from the reference cell to the current cell. This object was used
+ * to compute the information in the @p mapping_data object before the
+ * current function was called. It is also the mapping object that
+ * created the @p mapping_internal object via Mapping::get_data().
+ * You will need the reference to this mapping object most often
+ * to call Mapping::transform() to transform gradients and
+ * higher derivatives from the reference to the current cell.
+ * @param[in] mapping_internal An object specific to the mapping
+ * object. What the mapping chooses to store in there is of no
+ * relevance to the current function, but you may have to pass
+ * a reference to this object to certain functions of the
+ * Mapping class (e.g., Mapping::transform()) if you need to
+ * call them from the current function.
+ * @param[in] mapping_data The output object into which the
+ * Mapping::fill_fe_values() function wrote the mapping information
+ * corresponding to the current cell. This includes, for example,
+ * Jacobians of the mapping that may be of relevance to the
+ * current function, as well as other information that FEValues::reinit()
+ * requested from the mapping.
+ * @param[in] fe_internal A reference to an object previously
+ * created by get_data() and that may be used to store information
+ * the mapping can compute once on the reference cell. See the
+ * documentation of the FiniteElement::InternalDataBase class for an
+ * extensive description of the purpose of these objects.
+ * @param[out] output_data A reference to an object whose member
+ * variables should be computed. Not all of the members of this
+ * argument need to be filled; which ones need to be filled is
+ * determined by the update flags stored inside the
+ * @p fe_internal object.
+ */
virtual
void
fill_fe_subface_values (const typename Triangulation<dim,spacedim>::cell_iterator &cell,
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