proposition: Lemma restrict_ge0 D f : (forall x, D x -> 0 <= f x) -> forall x, 0 <= (f \_ D) x.
proof: Proof. by move=> f0 x; rewrite /patch; case: ifP => // /set_mem/f0->. Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg ssrnum ssrint interval finmap) mathcomp(mathcomp_extra boolp classical_sets fsbigop) mathcomp(functions cardinality set_interval) signed reals ereal topology normedtype sequences