proposition: Lemma powR_invn a n : 0 <= a -> a `^ (- n%:R) = a ^- n.
proof: Proof. by move=> a_ge0; rewrite powRN powR_mulrn. Qed.
imports: mathcomp(all_ssreflect ssralg ssrint ssrnum matrix) mathcomp(interval rat) mathcomp(boolp classical_sets functions) mathcomp(mathcomp_extra) reals ereal signed topology normedtype landau sequences derive realfun itv convex