type complex = {
    x : float;
    y : float;
  }

let iters1 max_iter xc yc =
  let rec aux count c =
    if count = max_iter then max_iter else begin
      if c.x *. c.x  +. c.y *. c.y >= 4.0 then count else begin
        aux (count+1) { x = c.x *. c.x -. c.y *. c.y +. xc;
                        y = 2.0 *. c.x *. c.y +. yc  }
      end
    end in
  aux 0 { x=xc; y=yc }