proposition: Lemma ln_div : {in Num.pos &, {morph ln : x y / x / y >-> x - y}}.
proof: Proof. move=> x y x0 y0; rewrite (lnM x0) ?lnV//. by move: y0; rewrite !qualifE/= invr_gt0. 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