In Curve: Rearranged for speed. arc_length_fun is now a property of Curve. If it is not supplied, it is computed via the derivative and spline fitting. Switching to the arc length parameterization is much faster now. The new stuff can be tested with testArcLength.m (which should be deleted after that).

% Choose the number of points on m, M, so that the step size is equal to that for N points on n.
function [M] = equal_step_size(n,N,m)
    M = round((m*(N-1)+n)/n);
end