proposition: Lemma sumRE (I : Type) (r : seq I) (P : pred I) (F : I -> R) : \sum_(i <- r | P i) F i = \big[+%R/0]_(i <- r | P i) F i.
proof: Proof. by []. Qed.
imports: mathcomp(all_ssreflect ssralg ssrnum) Reals mathcomp(lra) mathcomp(Rstruct)