proposition: Lemma cos_norm x : cos `|x| = cos x.
proof: Proof. by case: (ler0P x); rewrite ?cosN. Qed.
imports: mathcomp(all_ssreflect ssralg ssrint ssrnum matrix) mathcomp(interval rat) mathcomp(mathcomp_extra boolp classical_sets functions) reals ereal nsatz_realtype signed topology normedtype landau sequences derive realfun exp