proposition: Lemma nth_set_nth p n val k : nth (set_nth p n val) k = if k == n then val else nth p k.
proof: Proof. by rewrite /nth nth_set_nth. Qed.
imports: Coq(ZArith Reals) Coquelicot(Coquelicot) mathcomp.ssreflect(ssreflect ssrfun ssrbool eqtype ssrnat seq fintype bigop) Flocq(Core) Stdlib MathComp Interval Xreal Basic_rec