EICommon.m

classdef EICommon < Greedy.Plugin.Default
  % interface for GreedyPlugin.Interface implementations generating an empirical
  % interpolation basis
  %
  %

  properties
    % boolean flag specifying whether after the final extension step the
    % Lebesgue constant shall be computed and stored in the
    % Greedy.DataTree.Detailed.EILeafNode info fields.
    compute_lebesgue = true;
  end

  methods
    function  eiei = EICommon(generator)
      % function  eiei = EICommon(generator)
      % constructor for an EICommon instance
      %
      % Parameters:
      %   generator: object of type SnapshotsGenerator.SpaceOpEvals generating the (high
      %              dimensional) basis functions, i.e. operator or function
      %              evaluations.
      assert(isa(generator, 'SnapshotsGenerator.SpaceOpEvals'));
      eiei = eiei@Greedy.Plugin.Default(generator);
    end

    function [max_errs, max_err_sequence, max_mu_index] = error_estimators(this, rmodel, detailed_data, M_train)
      % function [max_errs, max_err_sequence, max_mu_index] = error_estimators(this, rmodel, detailed_data, M_train)
      % @copybrief Greedy.Plugin.Default.error_estimators()
      %
      % @copydetails Greedy.Plugin.Default.error_estimators()
      %
      % Parameters:
      %   rmodel: object of type IReducedModel
      %   detailed_data: object of type Greedy.DataTree.Detailed.EILeafNode
      %
      % @note This method is not implemented for empirical interpolation. There
      % is no known a posteriori error estimator.

      error(['No error estimators available for empirical interpolation. Use', ...
             'indicator_mode = ''error''']);
    end

    function detailed_data = finalize(this, rmodel, detailed_data)
      % function detailed_data = finalize(this, rmodel, detailed_data)
      % @copybrief Greedy.Plugin.Interface.finalize()
      %
      % @copydetails Greedy.Plugin.Interface.finalize()
      %
      % Parameters:
      %   rmodel: object of type IReducedModel
      %   detailed_data: object of type Greedy.DataTree.Detailed.EILeafNode
      %
      % Return values:
      %   detailed_data: object of type Greedy.DataTree.Detailed.EILeafNode
      %
      % This function actually computes the Lebesgue constant if indicated by
      % 'compute_lebesgue' and stores it in info fields.
      if this.compute_lebesgue
        QM = detailed_data.QM;
        BM = detailed_data.BM;
        XI = QM / BM;
        detailed_data.XI = XI;
        set_field(detailed_data, 'lebesgue', max(sum(abs(XI),2)));
        set_field(detailed_data, 'max_lebesgue', 2^size(BM,2) - 1);
      end
    end

    function merged = horzcat(this, varargin)
      % function merged = horzcat(varargin)
      % combines an arbitrary number of Greedy.Plugin.EI arguments to a big
      % one, with added SnapshotsGenerator.Cached instances.
      %
      % @sa SnapshotsGenerator.Cached.plus()
      %
      % Usage is like this:
      %  @code ei_ext_merged = [ ei_ext1, ei_ext2, ei_ext3 ]; @endcode
      %
      % Parameters:
      %   varargin: a list of Greedy.Plugin.EI instances to be combined.
      %
      % Return values:
      %   merged: a new object of type Greedy.Plugin.EI with combined
      %           generator member.
      mergedgen = this.generator;
      for i = 1:length(varargin)
        mergedgen = mergedgen + varargin{i}.generator;
      end
      %! \todo substitute the next line by some copy command
      merged = Greedy.Plugin.EI(mergedgen);
    end

    function summed = vertcat(this, varargin)
      % function merged = vertcat(varargin)
      % combines an arbitrary number of Greedy.Plugin.EI arguments to a
      % Greedy.Plugin.SummedEI instance.
      %
      % @sa Greedy.Plugin.SummedEI
      %
      % Usage is like this:
      %  @code ei_ext_sum = [ ei_ext1; ei_ext2; ei_ext3 ]; @endcode
      %
      % Parameters:
      %   varargin: a list of Greedy.Plugin.EI instances to be combined.
      %
      % Return values:
      %   merged: a new object of type Greedy.Plugin.SummedEI
      summed = Greedy.Plugin.SummedEI(this, varargin{:});
    end

  end

  methods(Abstract)

    % function cop = copy(this);
    % makes a deep copy of this extension instance
    %
    % Return values:
    %   cop:  a new instance of type EICommon which is a deep copy of this
    %         one.
    cop = copy(this);
  end

end