proposition: Lemma cos2pi : cos (pi *+ 2) = 1.
proof: Proof. by rewrite mulr2n cosD cospi sinpi !mulrN1 mulr0 subr0 opprK. 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