fact: Definition constant_sign (S : R -> Prop) (f : R -> R) := (forall x, S x -> 0 <= f x) \/ (forall x, S x -> f x <= 0).
imports: Coq(Reals List Psatz) Coquelicot(Coquelicot) mathcomp.ssreflect(ssreflect ssrfun ssrbool) Stdlib Coquelicot Xreal Interval Taylor_model Interval_compl