fzero_vec, integral_vec and spline are now local functions in Curve. Renamed arcLengthStretch to arcLengthParametrization. Removed plot_derivative. Added some comments and extra lines + removed unneccesary lines. arcLength is now a method and not static. Constructor does not accept difference operator anymore.

% runs f for each value in v and plots the result.
function plotfv(f,v,opt)

    if ~exist('opt')
        opt = '';
    end

    for i = 1:length(v)
        y(i) = f(v(i));
    end
    plot(v,y,opt)
end