proposition: Lemma eseries_cond {R : numFieldType} (f : (\bar R)^nat) P N : \sum_(N <= i <oo | P i) f i = \sum_(i <oo | P i && (N <= i)%N) f i.
proof: Proof. by apply/congr_lim/eq_fun => n /=; apply: big_nat_widenl. Qed.
imports: mathcomp(all_ssreflect ssralg ssrint ssrnum matrix) mathcomp(interval rat) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(set_interval) reals ereal signed topology normedtype landau