(*  sequence_limit.ml
 *
 *  Author: W. M. Farmer
 *  Revised: October 15, 2008
 *
 *  Description: The function seq_lim computes an approximation of 
 *               the limit of a sequence s : N -> R.  In some cases, 
 *               if s does not have a limit, seq_lim may return a 
 *               bogus limit.
 *)

let seq_lim s epsilon max_n =
  let abs x = if x >= 0. then x else (-. x) in
  let first = ref (s 0) in
  let second = ref (s 1) in 
  let n = ref 1 in
  while (abs (!first -. !second) >= epsilon) && !n < max_n do
    first := !second ;
    second := s (!n + 1) ;
    n := !n + 1
  done ;
  (!second, !n) ;;