Did you know that in numerical analysis , the error of an approximation of a function u {\displaystyle \textstyle u} by a polynomial of order at most m − 1 {\displaystyle \textstyle m-1} in terms of derivatives of u {\displaystyle \textstyle u} of order m {\displaystyle \textstyle m} is bound by the Bramble-Hilbert lemma ?