discfunc/common/l2project.m

function U = l2project(func,qdeg,grid,params)
%function U = l2project(func,qdeg,grid,params)
%
% function performing an l2 projection of an analytical function
% func to the discrete function space space. A quadrature of degree
% qdeg is used. params.pdeg specify the degree of the discrete fv function.
% the params.evaluate_basis must be set to the correct basis
% evaluation algorithm. params.element_quadrature is assumed to
% point to the correct element quadrature rule, i.e. triagrid, etc.
%
% result is U the column vector of dofs

% Bernard Haasdonk 3.9.2009

% result is a grid.nelements x params.ndofs_per_element matrix

params.grid = grid;
U = params.element_quadrature(qdeg,@func_phi_product,func, ...
                      params);

% multiply locally with inverse reference mass matrix
%Utmp = reshape(U,params.ndofs_per_element,grid.nelements);
M = params.local_mass_matrix(qdeg,params);
U = U * inv(M)';
U = U(:);
%| \docupdate