Create a new library symbol.ml.

[Faustine.git] / interpretor / signal.ml

diff --git a/interpretor/signal.ml b/interpretor/signal.ml
index b493b6c..ae312b0 100644 (file)
--- a/interpretor/signal.ml
+++ b/interpretor/signal.ml
@@ -32,7 +32,7 @@ class signal : int -> (time -> value_type) -> signal_type =
                  else raise (Signal_operation "frequency not matched.") in
            List.fold_left check self#frequency sl
 
-       method private add_memory : int -> unit = 
+       method add_memory : int -> unit = 
          fun (length : int) ->
            assert (length >= 0);
            if memory_length >= length then ()
@@ -141,10 +141,11 @@ class signal : int -> (time -> value_type) -> signal_type =
                    
        method prefix : signal_type -> signal_type =
            fun (s_init : signal_type) ->
+             let () = self#add_memory 1 in
              let func : time -> value_type = 
                fun t ->
                  if t = 0 then s_init#at 0
-                 else if t > 0 then self#at t
+                 else if t > 0 then self#at (t - 1) 
                  else raise (Signal_operation "prefix time < 0.") in
              new signal self#frequency func