IFemInfo.m

classdef IFemInfo < DataTree.INode
    % Abstract class for implementing finite elements.
    % Fem info classes implementing this interface are compatible with
    % Fem.DiscFunc
    
    % IM 29.11.2012
    
    properties (Abstract, SetAccess = private)
        
        % polynomial degree
        pdeg;
        
        % dimension of range space
        dimrange;
        
        % number of DOFs
        ndofs;
        
        % number of DOFs per grid element
        ndofs_per_element;
        
        % a (dimrange x number of scalar basis functions) matrix
        dof_ids_local;
        
        % grid of type .gridbase
        grid;
        
        % determinant of reference mapping
        detDF;
    end
    
    methods (Abstract)
        
        % evaluation of all basis functions in local coordinate
        evaluate_basis(obj, lcoord);
        
        % evaluation of the gradient of a scalar basis in local coordinate
        evaluate_scalar_basis_derivative(obj, lcoord, ncomp);
        
        % evaluation of i-th basis function in local coordinate
        evaluate_basis_function(obj, lcoord, i);
        
        % evaluation of the gradient of i-th basis function in local
        % coordinate
        evaluate_basis_function_derivative(obj, lcoord, i);    
        
        % returns entries of global-dof-map for several elements and several
        % local dof ids
        get_global_dof_index(obj, einds, gids);
        
        % returns global dof ids belonging to one component (indices into
        % DOF-vector)
        get_dof_ids_global(obj, ncomp);
        
        % returns an instance of Fem.DiscFunc which interpolates the given
        % analytical function, that can be evaluated at
        % (grid,elinds,lcoord,params)
        interpol_local(this, func, params)
    end
    
    methods
        
        function df = interpol_global(this, func, params)
            % interpolates a given analytical function that can be
            % evaluated at (glob, params)
            
            if nargin<3
                params = [];
            end
            
            df = this.interpol_local(@(grid, einds, lcoord, params) ...
                func(local2global(grid, einds, lcoord), params), params);
        end
    end
    
end