let mp6 = -. (3.1416 /. 6.)
let g = 9.80665
let l = 0.2

let pi0 = mp6
let pi1 = 0.
let pi2 = 0.

let acc x = -. g /. l *. (sin x)

let hybrid cradle2() =
  let rec der p0 = v0      init pi0 reset h01 -> last p1
      and der v0 = acc(p0) init 0.0 reset h01 -> last v1
      and der p1 = v1      init pi1 reset h01 -> last p0
      and der v1 = acc(p1) init 0.0 reset h01 -> last v0
      and h01 = up(last p0 -. last p1)
      and init h = -0.1
      and present h01 -> do h = -1.0 *. last h done
             else do der h = 0.0 done
  in (h, (p0, v0 /. 10.) , (p1, v1 /. 10.))

let hybrid cradle3() =
  let rec der p0 = v0      init pi0 reset h01 -> last p1
      and der v0 = acc(p0) init 0.0 reset h01 -> last v1
      and der p1 = v1      init pi1 reset h01 -> last p0 | h12 -> last p2
      and der v1 = acc(p1) init 0.0 reset h01 -> last v0 | h12 -> last v2
      and der p2 = v2      init pi2 reset h12 -> last p1
      and der v2 = acc(p2) init 0.0 reset h12 -> last v1
      and h01 = up(last p0 -. last p1)
      and h12 = up(last p1 -. last p2)
      and init h1 = -0.1
      and present h01 -> do h1 = -1.0 *. last h1 done else do der h1 = 0.0 done
      and init h2 = -0.1
      and present h12 -> do h2 = -1.0 *. last h2 done else do der h2 = 0.0 done
  in (p0, p1, p2, h1, h2)

let node print(v, s) =
  Format.printf "% .10e%s" v s

let hybrid main() =
  let der t = 1.0 init 0.0 in
  let (p0, p1, p2, h1, h2) = cradle3() in
  present (period(0.05)) -> (
    print(t, "\t");
	print(p0, "\t");
	print(p1, "\t");
	print(p2, "\t");
	print(h1, "\t");
	print(h2, "\n")
  ); ()