088be4cAn interactive tutorial on the Dirichlet problem, accuracy against costJeremy Magland 1function q = lp_orders(e, n)
2% LP_ORDERS Observed convergence order between successive refinements.
3%
4% q(k) = log(e(k-1)/e(k)) / log(n(k)/n(k-1)), and NaN wherever the ratio is not
5% a positive finite number (numbl's log of a NaN comes back complex, so the
6% guard is not optional).
7q = NaN(size(e));
8for k = 2:numel(e)
9 r = e(k-1) / e(k);
10 if isfinite(r) && r > 0
11 q(k) = log(r) / log(n(k) / n(k-1));
12 end
13end
14end