+ let transpose : 'a array array -> 'a array array =
+ fun matrix ->
+ let get_element = fun i -> fun array -> array.(i) in
+ let get_column = fun m -> fun i -> Array.map (get_element i) m in
+ Array.init self#width (get_column matrix) in
+ let value2float = fun (v : value_type) -> v#to_float_array in
+ let init = [|0.|] in
+ let container = Array.make length_max
+ (Array.make self#width init) in
+ let index = ref 0 in
+
+ try
+ while !index < length_max do
+ container.(!index) <- Array.map value2float (self#at !index);
+ incr index;
+ done;
+ transpose container
+
+ with x ->
+ match x with
+ | Invalid_argument s ->
+ transpose (Array.sub container 0 !index)
+ | _ -> raise x
+
+ method frequency : int array =
+ let each_rate : signal -> int =
+ fun (s : signal) ->
+ let rate = s#frequency in
+ if rate > 0 then rate
+ else if rate = 0 then 44100
+ else raise (Beam_matching "frequency error.") in
+ Array.map each_rate self#get
+