proposition: Lemma ln_pos x : 1 < x -> 0 < ln x.
proof: Proof. by move=> x0; rewrite -ln_1; exact: ln_increasing. Qed.
imports: mathcomp(all_ssreflect ssralg ssrnum) mathcomp(Rstruct) Reals Lra ssrR Reals_ext mathcomp(reals) realType_ext