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//---------------------------------------------------------------------------
//    $Id: error_estimator.h 18849 2009-05-15 17:59:46Z bangerth $
//    Version: $Name$
//
//    Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2008 by the deal.II authors
//
//    This file is subject to QPL and may not be  distributed
//    without copyright and license information. Please refer
//    to the file deal.II/doc/license.html for the  text  and
//    further information on this license.
//
//---------------------------------------------------------------------------
#ifndef __deal2__error_estimator_h
#define __deal2__error_estimator_h


#include <base/config.h>
#include <base/exceptions.h>
#include <base/function.h>
#include <base/multithread_info.h>
#include <dofs/function_map.h>
#include <map>

DEAL_II_NAMESPACE_OPEN


template <int, int> class DoFHandler;
template <int, int> class Mapping;
template <int> class Quadrature;

namespace hp
{
  template <int, int> class DoFHandler;
  template <int> class QCollection;
}



/**
 *  Implementation of the error estimator by Kelly, Gago, Zienkiewicz
 *  and Babuska.  This error estimator tries to approximate the error
 *  per cell by integration of the jump of the gradient of the
 *  solution along the faces of each cell.  It can be understood as a
 *  gradient recovery estimator; see the survey of Ainsworth for a
 *  complete discussion.
 *
 *  It seem as if this error estimator should only be valid for linear trial
 *  spaces, and there are indications that for higher order trial spaces the
 *  integrals computed here show superconvergence properties, i.e. they tend
 *  to zero faster than the error itself, thus ruling out the values as error
 *  indicators.
 *
 *  The error estimator really only estimates the error for the generalized
 *  Poisson equation $-\nabla\cdot a(x) \nabla u = f$ with either Dirichlet
 *  boundary conditions or generalized Neumann boundary conditions involving
 *  the conormal derivative $a\frac{du}{dn} = g$.
 *
 *  The error estimator returns a vector of estimated errors per cell which
 *  can be used to feed the <tt>Triangulation<dim>::refine_*</tt> functions. This
 *  vector contains elements of data type @p float, rather than @p double,
 *  since accuracy is not so important here, and since this can save rather
 *  a lot of memory, when using many cells.
 *
 *  
 *  <h3>Implementation</h3>
 *
 *  In principle, the implementation of the error estimation is simple: let
 *  \f[
 *  \eta_K^2 = \frac h{24} \int_{\partial K} \left[a \frac{\partial u_h}{\partial n}\right]^2 do
 *  \f]
 *  be the error estimator for cell $K$. $[\cdot]$ denotes the jump of the
 *  argument at the face. In the paper of Ainsworth, $h$ is divided by $24$,
 *  but this factor is a bit esoteric, stemming from interpolation estimates
 *  and stability constants which may hold for the Poisson problem, but may
 *  not hold for more general situations. In the implementation, this factor
 *  is considered, but may lead to wrong results. You may scale the vector
 *  appropriately afterwards.
 *
 *  To perform the integration, use is made of the FEFaceValues and
 *  FESubfaceValues classes. The integration is performed by looping
 *  over all cells and integrating over faces that are not yet treated.
 *  This way we avoid integration on faces twice, once for each time we
 *  visit one of the adjacent cells. In a second loop over all cells, we
 *  sum up the contributions of the faces (which are the integrated
 *  square of the jumps) of each cell and take the square root.
 *
 *  The integration is done using a quadrature formula on the face.
 *  For linear trial functions (FEQ1), the QGauss2 or even the
 *  QMidpoint rule will suffice. For higher order elements, it is
 *  necessary to utilize higher order quadrature formulae as well.
 *
 *  We store the contribution of each face in a @p map, as provided by the
 *  C++ standard library, with the iterator pointing to that face being the
 *  key into the map. In fact, we do not store the indicator per face, but
 *  only the integral listed above. When looping the second time over all
 *  cells, we have to sum up the contributions of the faces, multiply them
 *  with $\frac h{24}$ and take the square root. By doing the multiplication
 *  with $h$ in the second loop, we avoid problems to decide with which $h$
 *  to multiply, that of the cell on the one or that of the cell on the other
 *  side of the face.
 *
 *  $h$ is taken to be the greatest length of the diagonals of the cell. For
 *  more or less uniform cells without deformed angles, this coincides with
 *  the diameter of the cell.
 *  
 *
 *  <h3>Vector-valued functions</h3>
 *
 *  If the finite element field for which the error is to be estimated
 *  is vector-valued, i.e. the finite element has more than one
 *  component, then all the above can be applied to all or only some
 *  components at the same time. The main function of this class takes
 *  a list of flags denoting the components for which components the
 *  error estimator is to be applied; by default, it is a list of only
 *  @p trues, meaning that all variables shall be treated.
 *
 *  In case the different components of a field have different
 *  physical meaning (for example velocity and pressure in the Stokes
 *  equations), it would be senseless to use the same coefficient for
 *  all components. In that case, you can pass a function with as many
 *  components as there are components in the finite element field and
 *  each component of the error estimator will then be weighted by the
 *  respective component in this coefficient function. In the other
 *  case, when all components have the same meaning (for example the
 *  displacements in Lame's equations of elasticity), you can specify
 *  a scalar coefficient which will then be used for all components.
 *
 *
 *  <h3>%Boundary values</h3>
 *  
 *  If the face is at the boundary, i.e. there is no neighboring cell to which
 *  the jump in the gradiend could be computed, there are two possibilities:
 *  <ul>
 *  <li> The face belongs to a Dirichlet boundary. Then the face is not
 *    considered, which can be justified looking at a dual problem technique and
 *    should hold exactly if the boundary can be approximated exactly by the
 *    finite element used (i.e. it is a linear boundary for linear finite elements,
 *    quadratic for isoparametric quadratic elements, etc). For boundaries which
 *    can not be exactly approximated, one should consider the difference
 *    $z-z_h$ on the face, $z$ being a dual problem's solution which is zero at
 *    the true boundary and $z_h$ being an approximation, which in most cases
 *    will be zero on the numerical boundary. Since on the numerical boundary
 *    $z$ will not be zero in general, we would get another term here, but this
 *    one is neglected for practical reasons, in the hope that the error made
 *    here will tend to zero faster than the energy error we wish to estimate.
 *
 *    Though no integration is necessary, in the list of face contributions we
 *    store a zero for this face, which makes summing up the contributions of
 *    the different faces to the cells easier.
 *
 *  <li> The face belongs to a Neumann boundary.  In this case, the
 *    contribution of the face $F\in\partial K$ looks like
 *    \f[ \int_F \left|g-a\frac{\partial u_h}{\partial n}\right|^2 ds \f]
 *    where $g$ is the Neumann boundary function. If the finite element is
 *    vector-valued, then obviously the function denoting the Neumann boundary
 *    conditions needs to be vector-valued as well.
 *
 *  <li> No other boundary conditions are considered.
 *  </ul>
 *  The object describing the boundary conditions is obtained from the
 *  triangulation.
 *
 *  Thanks go to Franz-Theo Suttmeier for clarifications about boundary
 *  conditions.
 *
 *  
 *  <h3>Handling of hanging nodes</h3>
 *  
 *  The integration along faces with hanging nodes is quite tricky, since one
 *  of the elements has to be shifted one level up or down. See the
 *  documentation for the FESubFaceValues class for more information about
 *  technical issues regarding this topic.
 *
 *  In praxi, since we integrate over each face only once, we do this when we
 *  are on the coarser one of the two cells adjacent to a subface (a subface
 *  is defined to be the child of a face; seen from the coarse cell, it is a
 *  subface, while seen from the refined cell it is one of its faces). The
 *  reason is that finding neighborship information is a bit easier then, but
 *  that's all practical reasoning, nothing fundamental.
 *
 *  Since we integrate from the coarse side of the face, we have the mother
 *  face readily at hand and store the result of the integration over that
 *  mother face (being the sum of the integrals along the subfaces) in the
 *  abovementioned map of integrals as well. This consumes some memory more
 *  than needed, but makes the summing up of the face contributions to the
 *  cells easier, since then we have the information from all faces of all
 *  cells at hand and need not think about explicitly determining whether
 *  a face was refined or not. The same applies for boundary faces, see
 *  above.
 *
 *
 *  <h3>Multiple solution vectors</h3>
 *
 *  In some cases, for example in time-dependent problems, one would
 *  like to compute the error estimates for several solution vectors
 *  on the same grid at once, with the same coefficients, boundary
 *  condition object, etc, e.g. for the solutions on several
 *  successive time steps. One could then call the functions of this
 *  class several times for each solution. However, the largest factor
 *  in the computation of the error estimates (in terms of computing
 *  time) is initialization of FEFaceValues and FESubFaceValues
 *  objects, and iterating through all faces and subfaces. If the
 *  solution vectors live on the same grid, this effort can be reduced
 *  significantly by treating all solution vectors at the same time,
 *  initializing the FEFaceValues objects only once per cell and for
 *  all solution vectors at once, and also only looping through the
 *  triangulation only once. For this reason, besides the @p estimate
 *  function in this class that takes a single input vector and
 *  returns a single output vector, there is also a function that
 *  accepts several in- and output vectors at the same time.
 *
 *  @ingroup numerics
 *  @author Wolfgang Bangerth, 1998, 1999, 2000, 2004, 2006; parallelization by Thomas Richter, 2000
 */
template <int dim, int spacedim=dim>
class KellyErrorEstimator
{
  public:
				     /**
				      * Implementation of the error
				      * estimator described above. You
				      * may give a coefficient, but
				      * there is a default value which
				      * denotes the constant
				      * coefficient with value
				      * one. The coefficient function
				      * may either be a scalar one, in
				      * which case it is used for all
				      * components of the finite
				      * element, or a vector-valued
				      * one with as many components as
				      * there are in the finite
				      * element; in the latter case,
				      * each component is weighted by
				      * the respective component in
				      * the coefficient.
				      *
				      * You might give a list of
				      * components you want to
				      * evaluate, in case the finite
				      * element used by the
				      * DoFHandler object is
				      * vector-valued. You then have
				      * to set those entries to true
				      * in the bit-vector
				      * @p component_mask for which the
				      * respective component is to be
				      * used in the error
				      * estimator. The default is to
				      * use all components, which is
				      * done by either providing a
				      * bit-vector with all-set
				      * entries, or an empty
				      * bit-vector.
				      *
				      * The @p subdomain_id parameter
				      * indicates whether we shall compute
				      * indicators for all cells (in case its
				      * value is the default,
				      * <tt>numbers::invalid_unsigned_int</tt>),
				      * or only for the cells belonging to a
				      * certain subdomain with the given
				      * indicator. The latter case is used for
				      * parallel computations where all
				      * processor nodes have the global grid
				      * stored, and could well compute all the
				      * indicators for all cells themselves,
				      * but where it is more efficient to have
				      * each process compute only indicators
				      * for the cells it owns, and have them
				      * exchange the resulting information
				      * afterwards. This is in particular true
				      * for the case where meshes are very
				      * large and computing indicators for @em
				      * every cells is too expensive, while
				      * computing indicators for only local
				      * cells is acceptable. Note that if you
				      * only ask for the indicators of a
				      * certain subdomain to be computed, you
				      * must nevertheless make sure that this
				      * function has access to the correct
				      * node values of @em all degrees of
				      * freedom. This is since the function
				      * needs to access DoF values on
				      * neighboring cells as well, even if
				      * they belong to a different subdomain.
				      *
				      * The @p material_id parameter has a
				      * similar meaning: if not set to its
				      * default value, it means that
				      * indicators will only be computed for
				      * cells with this particular material
				      * id.
				      *
				      * The @p n_threads parameter used to
				      * indicate the number of threads to be
				      * used to compute the error
				      * estimator. This parameter is now
				      * ignored, with the number of threads
				      * determined automatically. The
				      * parameter is retained for
				      * compatibility with old versions of the
				      * library.
				      */
    template <typename InputVector, class DH>
    static void estimate (const Mapping<dim, spacedim>      &mapping,
			  const DH                &dof,
			  const Quadrature<dim-1> &quadrature,
			  const typename FunctionMap<dim>::type &neumann_bc,
			  const InputVector       &solution,
			  Vector<float>           &error,
			  const std::vector<bool> &component_mask = std::vector<bool>(),
			  const Function<dim>     *coefficients   = 0,
			  const unsigned int       n_threads = multithread_info.n_default_threads,
                          const unsigned int       subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int       material_id = numbers::invalid_unsigned_int);
    
				     /**
				      * Calls the @p estimate
				      * function, see above, with
				      * <tt>mapping=MappingQ1@<dim@>()</tt>.
				      */    
    template <typename InputVector, class DH>
    static void estimate (const DH                &dof,
			  const Quadrature<dim-1> &quadrature,
			  const typename FunctionMap<dim>::type &neumann_bc,
			  const InputVector       &solution,
			  Vector<float>           &error,
			  const std::vector<bool> &component_mask = std::vector<bool>(),
			  const Function<dim>     *coefficients   = 0,
			  const unsigned int       n_threads = multithread_info.n_default_threads,
                          const unsigned int       subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int       material_id = numbers::invalid_unsigned_int);
    
				     /**
				      * Same function as above, but
				      * accepts more than one solution
				      * vector and returns one error
				      * vector for each solution
				      * vector. For the reason of
				      * existence of this function,
				      * see the general documentation
				      * of this class.
				      *
				      * Since we do not want to force
				      * the user of this function to
				      * copy around their solution
				      * vectors, the vector of
				      * solution vectors takes
				      * pointers to the solutions,
				      * rather than being a vector of
				      * vectors. This makes it simpler
				      * to have the solution vectors
				      * somewhere in memory, rather
				      * than to have them collected
				      * somewhere special. (Note that
				      * it is not possible to
				      * construct of vector of
				      * references, so we had to use a
				      * vector of pointers.)
				      */
    template <typename InputVector, class DH>
    static void estimate (const Mapping<dim, spacedim>          &mapping,
			  const DH                    &dof,
			  const Quadrature<dim-1>     &quadrature,
			  const typename FunctionMap<dim>::type &neumann_bc,
			  const std::vector<const InputVector *> &solutions,
			  std::vector<Vector<float>*> &errors,
			  const std::vector<bool>     &component_mask = std::vector<bool>(),
			  const Function<dim>         *coefficients   = 0,
			  const unsigned int           n_threads = multithread_info.n_default_threads,
                          const unsigned int           subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int           material_id = numbers::invalid_unsigned_int);

				     /**
				      * Calls the @p estimate
				      * function, see above, with
				      * <tt>mapping=MappingQ1@<dim@>()</tt>.
				      */
    template <typename InputVector, class DH>
    static void estimate (const DH                    &dof,
			  const Quadrature<dim-1>     &quadrature,
			  const typename FunctionMap<dim>::type &neumann_bc,
			  const std::vector<const InputVector *> &solutions,
			  std::vector<Vector<float>*> &errors,
			  const std::vector<bool>     &component_mask = std::vector<bool>(),
			  const Function<dim>         *coefficients   = 0,
			  const unsigned int           n_threads = multithread_info.n_default_threads,
                          const unsigned int           subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int           material_id = numbers::invalid_unsigned_int);


				     /**
				      * Equivalent to the set of functions
				      * above, except that this one takes a
				      * quadrature collection for hp finite
				      * element dof handlers.
				      */
    template <typename InputVector, class DH>
    static void estimate (const Mapping<dim, spacedim>      &mapping,
			  const DH                &dof,
			  const hp::QCollection<dim-1> &quadrature,
			  const typename FunctionMap<dim>::type &neumann_bc,
			  const InputVector       &solution,
			  Vector<float>           &error,
			  const std::vector<bool> &component_mask = std::vector<bool>(),
			  const Function<dim>     *coefficients   = 0,
			  const unsigned int       n_threads = multithread_info.n_default_threads,
                          const unsigned int       subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int       material_id = numbers::invalid_unsigned_int);


				     /**
				      * Equivalent to the set of functions
				      * above, except that this one takes a
				      * quadrature collection for hp finite
				      * element dof handlers.
				      */
    template <typename InputVector, class DH>
    static void estimate (const DH                &dof,
			  const hp::QCollection<dim-1> &quadrature,
			  const typename FunctionMap<dim>::type &neumann_bc,
			  const InputVector       &solution,
			  Vector<float>           &error,
			  const std::vector<bool> &component_mask = std::vector<bool>(),
			  const Function<dim>     *coefficients   = 0,
			  const unsigned int       n_threads = multithread_info.n_default_threads,
                          const unsigned int       subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int       material_id = numbers::invalid_unsigned_int);


				     /**
				      * Equivalent to the set of functions
				      * above, except that this one takes a
				      * quadrature collection for hp finite
				      * element dof handlers.
				      */
    template <typename InputVector, class DH>
    static void estimate (const Mapping<dim, spacedim>          &mapping,
			  const DH                    &dof,
			  const hp::QCollection<dim-1> &quadrature,
			  const typename FunctionMap<dim>::type &neumann_bc,
			  const std::vector<const InputVector *> &solutions,
			  std::vector<Vector<float>*> &errors,
			  const std::vector<bool>     &component_mask = std::vector<bool>(),
			  const Function<dim>         *coefficients   = 0,
			  const unsigned int           n_threads = multithread_info.n_default_threads,
                          const unsigned int           subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int           material_id = numbers::invalid_unsigned_int);


				     /**
				      * Equivalent to the set of functions
				      * above, except that this one takes a
				      * quadrature collection for hp finite
				      * element dof handlers.
				      */
    template <typename InputVector, class DH>
    static void estimate (const DH                    &dof,
			  const hp::QCollection<dim-1> &quadrature,
			  const typename FunctionMap<dim>::type &neumann_bc,
			  const std::vector<const InputVector *> &solutions,
			  std::vector<Vector<float>*> &errors,
			  const std::vector<bool>     &component_mask = std::vector<bool>(),
			  const Function<dim>         *coefficients   = 0,
			  const unsigned int           n_threads = multithread_info.n_default_threads,
                          const unsigned int           subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int           material_id = numbers::invalid_unsigned_int);
    
    
				     /**
				      * Exception
				      */
    DeclException0 (ExcInvalidBoundaryIndicator);
				     /**
				      * Exception
				      */
    DeclException0 (ExcInvalidComponentMask);
				     /**
				      * Exception
				      */
    DeclException0 (ExcInvalidCoefficient);
				     /**
				      * Exception
				      */
    DeclException0 (ExcInvalidBoundaryFunction);
				     /**
				      * Exception
				      */
    DeclException2 (ExcIncompatibleNumberOfElements,
		    int, int,
		    << "The number of elements " << arg1 << " and " << arg2
		    << " of the vectors do not match!");
				     /**
				      * Exception
				      */
    DeclException0 (ExcInvalidSolutionVector);
				     /**
				      * Exception
				      */
    DeclException0 (ExcNoSolutions);
};



/**
 * This is a specialization of the general template for 1d. The implementation
 * is sufficiently different for 1d to justify this specialization. The basic
 * difference between 1d and all other space dimensions is that in 1d, there
 * are no faces of cells, just the vertices between line segments, so we have
 * to compute the jump terms differently. However, this class offers exactly
 * the same public functions as the general template, so that a user will not
 * see any difference.
 *
 * @author Wolfgang Bangerth, 1998, 2004.
 */
template <int spacedim>
class KellyErrorEstimator<1,spacedim>
{
  public:
				     /**
				      * Implementation of the error
				      * estimator described above. You
				      * may give a coefficient, but
				      * there is a default value which
				      * denotes the constant
				      * coefficient with value
				      * one. The coefficient function
				      * may either be a scalar one, in
				      * which case it is used for all
				      * components of the finite
				      * element, or a vector-valued
				      * one with as many components as
				      * there are in the finite
				      * element; in the latter case,
				      * each component is weighted by
				      * the respective component in
				      * the coefficient.
				      *
				      * You might give a list of components
				      * you want to evaluate, in case the
				      * finite element used by the DoFHandler
				      * object is vector-valued. You then have
				      * to set those entries to true in the
				      * bit-vector @p component_mask for which
				      * the respective component is to be used
				      * in the error estimator. The default is
				      * to use all components, which is done
				      * by either providing a bit-vector with
				      * all-set entries, or an empty
				      * bit-vector. All the other parameters
				      * are as in the general case used for 2d
				      * and higher.
				      *
				      * The estimator supports multithreading
				      * and splits the cells to
				      * <tt>multithread_info.n_default_threads</tt>
				      * (default) threads. The number of
				      * threads to be used in multithreaded
				      * mode can be set with the last
				      * parameter of the error estimator.
				      * Multithreading is not presently
				      * implemented for 1d, but we retain the
				      * respective parameter for compatibility
				      * with the function signature in the
				      * general case.
				      */
    template <typename InputVector, class DH>
    static void estimate (const Mapping<1,spacedim>  &mapping,
			  const DH   &dof,
			  const Quadrature<0> &quadrature,
			  const FunctionMap<1>::type &neumann_bc,
			  const InputVector       &solution,
			  Vector<float>           &error,
			  const std::vector<bool> &component_mask = std::vector<bool>(),
			  const Function<1>     *coefficients   = 0,
			  const unsigned int       n_threads = multithread_info.n_default_threads,
                          const unsigned int       subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int       material_id = numbers::invalid_unsigned_int);

				     /**
				      * Calls the @p estimate
				      * function, see above, with
				      * <tt>mapping=MappingQ1<1>()</tt>.
				      */    
    template <typename InputVector, class DH>
    static void estimate (const DH   &dof,
			  const Quadrature<0> &quadrature,
			  const FunctionMap<1>::type &neumann_bc,
			  const InputVector       &solution,
			  Vector<float>           &error,
			  const std::vector<bool> &component_mask = std::vector<bool>(),
			  const Function<1>     *coefficients   = 0,
			  const unsigned int       n_threads = multithread_info.n_default_threads,
                          const unsigned int       subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int       material_id = numbers::invalid_unsigned_int);
    
				     /**
				      * Same function as above, but
				      * accepts more than one solution
				      * vectors and returns one error
				      * vector for each solution
				      * vector. For the reason of
				      * existence of this function,
				      * see the general documentation
				      * of this class.
				      *
				      * Since we do not want to force
				      * the user of this function to
				      * copy around their solution
				      * vectors, the vector of
				      * solution vectors takes
				      * pointers to the solutions,
				      * rather than being a vector of
				      * vectors. This makes it simpler
				      * to have the solution vectors
				      * somewhere in memory, rather
				      * than to have them collected
				      * somewhere special. (Note that
				      * it is not possible to
				      * construct of vector of
				      * references, so we had to use a
				      * vector of pointers.)
				      */
    template <typename InputVector, class DH>
    static void estimate (const Mapping<1,spacedim>          &mapping,
			  const DH       &dof,
			  const Quadrature<0>     &quadrature,
			  const FunctionMap<1>::type &neumann_bc,
			  const std::vector<const InputVector *> &solutions,
			  std::vector<Vector<float>*> &errors,
			  const std::vector<bool>     &component_mask = std::vector<bool>(),
			  const Function<1>         *coefficients   = 0,
			  const unsigned int           n_threads = multithread_info.n_default_threads,
                          const unsigned int           subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int           material_id = numbers::invalid_unsigned_int);

				     /**
				      * Calls the @p estimate
				      * function, see above, with
				      * <tt>mapping=MappingQ1<1>()</tt>.
				      */
    template <typename InputVector, class DH>
    static void estimate (const DH       &dof,
			  const Quadrature<0>     &quadrature,
			  const FunctionMap<1>::type &neumann_bc,
			  const std::vector<const InputVector *> &solutions,
			  std::vector<Vector<float>*> &errors,
			  const std::vector<bool>     &component_mask = std::vector<bool>(),
			  const Function<1>         *coefficients   = 0,
			  const unsigned int           n_threads = multithread_info.n_default_threads,
                          const unsigned int           subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int           material_id = numbers::invalid_unsigned_int);


				     /**
				      * Equivalent to the set of functions
				      * above, except that this one takes a
				      * quadrature collection for hp finite
				      * element dof handlers.
				      */
    template <typename InputVector, class DH>
    static void estimate (const Mapping<1,spacedim>      &mapping,
			  const DH                &dof,
			  const hp::QCollection<0> &quadrature,
			  const typename FunctionMap<1>::type &neumann_bc,
			  const InputVector       &solution,
			  Vector<float>           &error,
			  const std::vector<bool> &component_mask = std::vector<bool>(),
			  const Function<1>     *coefficients   = 0,
			  const unsigned int       n_threads = multithread_info.n_default_threads,
                          const unsigned int       subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int       material_id = numbers::invalid_unsigned_int);


				     /**
				      * Equivalent to the set of functions
				      * above, except that this one takes a
				      * quadrature collection for hp finite
				      * element dof handlers.
				      */
    template <typename InputVector, class DH>
    static void estimate (const DH                &dof,
			  const hp::QCollection<0> &quadrature,
			  const typename FunctionMap<1>::type &neumann_bc,
			  const InputVector       &solution,
			  Vector<float>           &error,
			  const std::vector<bool> &component_mask = std::vector<bool>(),
			  const Function<1>     *coefficients   = 0,
			  const unsigned int       n_threads = multithread_info.n_default_threads,
                          const unsigned int       subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int       material_id = numbers::invalid_unsigned_int);


				     /**
				      * Equivalent to the set of functions
				      * above, except that this one takes a
				      * quadrature collection for hp finite
				      * element dof handlers.
				      */
    template <typename InputVector, class DH>
    static void estimate (const Mapping<1,spacedim>          &mapping,
			  const DH                    &dof,
			  const hp::QCollection<0> &quadrature,
			  const typename FunctionMap<1>::type &neumann_bc,
			  const std::vector<const InputVector *> &solutions,
			  std::vector<Vector<float>*> &errors,
			  const std::vector<bool>     &component_mask = std::vector<bool>(),
			  const Function<1>         *coefficients   = 0,
			  const unsigned int           n_threads = multithread_info.n_default_threads,
                          const unsigned int           subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int           material_id = numbers::invalid_unsigned_int);


				     /**
				      * Equivalent to the set of functions
				      * above, except that this one takes a
				      * quadrature collection for hp finite
				      * element dof handlers.
				      */
    template <typename InputVector, class DH>
    static void estimate (const DH                    &dof,
			  const hp::QCollection<0> &quadrature,
			  const typename FunctionMap<1>::type &neumann_bc,
			  const std::vector<const InputVector *> &solutions,
			  std::vector<Vector<float>*> &errors,
			  const std::vector<bool>     &component_mask = std::vector<bool>(),
			  const Function<1>         *coefficients   = 0,
			  const unsigned int           n_threads = multithread_info.n_default_threads,
                          const unsigned int           subdomain_id = numbers::invalid_unsigned_int,
                          const unsigned int           material_id = numbers::invalid_unsigned_int);
    
				     /**
				      * Exception
				      */
    DeclException0 (ExcInvalidBoundaryIndicator);
				     /**
				      * Exception
				      */
    DeclException0 (ExcInvalidComponentMask);
				     /**
				      * Exception
				      */
    DeclException0 (ExcInvalidCoefficient);
				     /**
				      * Exception
				      */
    DeclException0 (ExcInvalidBoundaryFunction);
				     /**
				      * Exception
				      */
    DeclException2 (ExcIncompatibleNumberOfElements,
		    int, int,
		    << "The number of elements " << arg1 << " and " << arg2
		    << " of the vectors do not match!");
				     /**
				      * Exception
				      */
    DeclException0 (ExcInvalidSolutionVector);
				     /**
				      * Exception
				      */
    DeclException0 (ExcNoSolutions);
};



DEAL_II_NAMESPACE_CLOSE

#endif