open Jog open Zone;;
let top = [[0; 1; 2; 3; 4]; [0; 1; 2; 4; 5]; [0; 1; 2; 5; 3]] in
let ini = ref (fun _ -> raise (OffTrack 3)) in
let bndry = Glue.morphgen (nz (fun i j -> if i=j then 0. else 1.)) top
    [([0; 1; 2; 3], ((fun  x -> x),
      (fun t -> ini := t.curl; {t with curl = (fun (k, ball) -> ball)})))] in
    (bndry, !ini (3, Linear.iden 4));;

(* (_, [|[|0.437500000000000056; -0.5625; -0.5625;
     -0.838525491562421|];
   [|-0.5625; 0.4375; -0.5625; -0.838525491562421|];
   [|-0.5625; -0.5625; 0.4375; -0.838525491562421|];
   [|0.209631372890605377; 0.20963137289060535; 0.20963137289060535;
     -0.6875|]|]) *)