(*********************************************************)
(** ** Square function                                   *)
(*********************************************************)

Definition Rsqr r : R := r * r.Notation "r ²" := (Rsqr r) (at level 1, format "r ²") : R_scope.

Lemma Rmult_le_ge_compat_neg_l : forall r r1 r2, r <= 0 -> r1 <= r2 -> r * r1 >= r * r2.