proposition: Lemma derivable_xlnx_total x : 0 < x -> derivable_pt xlnx_total x.
proof: Proof. move=> x_pos. apply derivable_pt_mult. by apply derivable_id. by apply derivable_pt_ln. Defined.
imports: mathcomp(all_ssreflect ssralg ssrnum) mathcomp(Rstruct) Reals Lra ssrR realType_ext Reals_ext Ranalysis_ext logb convex