// $Id: error_vector.h 2501 2007-11-20 02:33:29Z benkirk $// The libMesh Finite Element Library.// Copyright (C) 2002-2007  Benjamin S. Kirk, John W. Peterson  // This library is free software; you can redistribute it and/or// modify it under the terms of the GNU Lesser General Public// License as published by the Free Software Foundation; either// version 2.1 of the License, or (at your option) any later version.  // This library is distributed in the hope that it will be useful,// but WITHOUT ANY WARRANTY; without even the implied warranty of// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU// Lesser General Public License for more details.  // You should have received a copy of the GNU Lesser General Public// License along with this library; if not, write to the Free Software// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA#ifndef __error_vector_h__#define __error_vector_h__// C++ includes// Local Includes#include "statistics.h"// Now defined in libmesh_common.h:// typedef float ErrorVectorReal;// Forward Declarationsclass MeshBase;class Mesh;/** * The \p ErrorVector is a specialization of the * \p StatisticsVector for error data computed on a finite element * mesh.  In general, when computing the error on a mesh only the * active elements are considered, but the \p ErrorVector is sized * according to the total number of elements in the mesh.  The * \p ErrorVector is thus padded with zeros for all the inactive * elements, and this must be taken into account when calculating * the statistics.  Since the error is a positive quantity this class * assumes it contains positive data (i.e. min_val >= 0.). * * @author Benjamin S. Kirk, 2003. */class ErrorVector : public StatisticsVector<ErrorVectorReal>{  public:    /**   * ErrorVector constructor; sets initial length to \p i.   *   * If mesh is not null, MeshBase::elem() and Elem::is_active() will   * be used to distinguish active and inactive elements.  If mesh is null,   * ErrorVector will assume that all 0.0 error values correspond to inactive   * elements and all non-zero error values correspond to active elements.   */  ErrorVector(unsigned int i=0, MeshBase *mesh = NULL) : StatisticsVector<ErrorVectorReal> (i), _mesh(mesh) {}    /**   * ErrorVector constructor; sets initial length to \p i and initial values to \p val.   *   * If mesh is not null, MeshBase::elem() and Elem::is_active() will   * be used to distinguish active and inactive elements.  If mesh is null,   * ErrorVector will assume that all 0.0 error values correspond to inactive   * elements and all non-zero error values correspond to active elements.   */  ErrorVector(unsigned int i, ErrorVectorReal val) :      StatisticsVector<ErrorVectorReal> (i,val) {}  /**   * Returns the minimum nonzero value in the data set.   */  virtual ErrorVectorReal minimum() const;  /**   * Returns the mean value of the data set. Ignores   * zero values.   */  virtual Real mean() const;    /**   * Returns the median (e.g. the middle)   * value of the data set, ignoring inactive elements.   * This function modifies the   * original data by sorting, so it   * can't be called on const objects.   * Source: GNU Scientific Library   */  virtual Real median();  /**   * A const version of the median funtion.   * Requires twice the memory of original   * data set but does not change the original.   */  virtual Real median() const;  /**   * Computes the variance of the data set   * ignoring inactive elements.   * Uses a recurrence relation to prevent   * data overflow for large sums.   * Note: The variance is equal to the   * standard deviation squared.  The variance   * is normalized by N in this case.   * Source: GNU Scientific Library   */  virtual Real variance() const  { return this->variance(this->mean()); }  /**      * Computes the variance of the data set   * ignoring inactive elements.   * where the \p mean is provided. This is useful   * for efficiency when you have already calculated   * the mean. Uses a recurrence relation to prevent   * data overflow for large sums.   * Note: The variance is equal to the   * standard deviation squared.   * Source: GNU Scientific Library   */  virtual Real variance(const Real mean) const;  /**   * Returns a vector of unsigned ints which correspond   * to the indices of every member of the data set   * below the cutoff value cut ignoring inactive elements.   */  virtual std::vector<unsigned int> cut_below(Real cut) const;  /**   * Returns a vector of unsigned ints which correspond   * to the indices of every member of the data set   * above the cutoff value cut ignoring inactive elements.   */  virtual std::vector<unsigned int> cut_above(Real cut) const;  /**   * Plots a data file, of a type determined by looking at   * the file extension in \p filename, of the error values on   * the active elements of \p mesh.   */  void plot_error(const std::string &filename,		  const MeshBase& mesh) const;protected:  /**   * Utility function to decide whether element i is active   */  bool is_active_elem (unsigned int i) const;  /**   * Pointer to the mesh, which may be used to decide which   * elements are active   */  MeshBase *_mesh;};#endif