fact: Definition index_iotaz (mi ni : int) := match mi, ni with | Posz _, Negz _ => [::] | Posz m, Posz n => map Posz (index_iota m n) | Negz m, Negz n => map Negz (rev (index_iota n.+1 m.+1)) | Negz m, Posz n => rev (map Negz (index_iota 0 m.+1)) ++ (map Posz (index_iota 0 n)) end.
imports: mathcomp(all_ssreflect all_algebra) extra_mathcomp