proposition: Lemma floor_itv x : x \is Rreal -> (floor x)%:~R <= x < (floor x + 1)%:~R.
proof: Proof. by case: (x \is _) (floorP x). Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype bigop order ssralg poly ssrnum ssrint)