% Useful for evaulating forcing functions with different functional expressions for each block
% f: cell array of function handles fi
% f_i = f_i(x1,y,...,t)
% t: time point. If not specified, it is assumed that the functions take only spatial arguments.
function gf = evalOn(g, f, t)
    default_arg('t',[]);

    grids = g.grids;
    nBlocks = length(grids);
    gf = cell(nBlocks,1);

    if isempty(t)
        for i = 1:nBlocks
            grid.evalOn(grids{i}, f{i} );
        end
    else
        dim = nargin(f{1}) - 1;
        for i = 1:nBlocks
            switch dim
                case 1
                    gf{i} = grid.evalOn(grids{i}, @(x)f{i}(x,t) );
                case 2
                    gf{i} = grid.evalOn(grids{i}, @(x,y)f{i}(x,y,t) );
                case 3
                    gf{i} = grid.evalOn(grids{i}, @(x,y,z)f{i}(x,y,z,t) );
            end
        end
    end

    gf = blockmatrix.toMatrix(gf);
end