fact: Definition nseries (u : nat^nat) := (fun n => \sum_(0 <= k < n) u k)%N.
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