diff --git a/Parallel/Parallel.ml b/Parallel/Parallel.ml
index 7f2db2e..f27b66d 100644
--- a/Parallel/Parallel.ml
+++ b/Parallel/Parallel.ml
@@ -23,7 +23,7 @@ let barrier () =
 
 module Vec = struct
 
-  type t =
+  type t = 
   {
     global_first : int ; (* Lower  index in the global array *)
     global_last  : int ; (* Higher index in the global array *)
@@ -32,6 +32,15 @@ module Vec = struct
     data         : Lacaml.D.vec ; (* Lacaml vector containing the data *)
   }
 
+  let dim vec =
+    vec.global_last - vec.global_first + 1
+
+  let local_first  vec = vec.local_first
+  let local_last   vec = vec.local_last 
+  let global_first vec = vec.global_first
+  let global_last  vec = vec.global_last 
+  let data         vec = vec.data
+
   let pp ppf v =
     Format.fprintf ppf "@[<2>";
     Format.fprintf ppf "@[ gf : %d@]@;" v.global_first;
@@ -93,7 +102,7 @@ module Vec = struct
 
 
   let to_array vec = 
-    let final_size = vec.global_last - vec.global_first + 1 in
+    let final_size = dim vec in
     let buffer_size = (Lacaml.D.Vec.dim vec.data) * size in
     let buffer = Array.make buffer_size 0. in
     let data = Lacaml.D.Vec.to_array vec.data in
@@ -113,4 +122,17 @@ module Vec = struct
     to_array v
     |> Lacaml.D.Vec.of_array
     
+
 end
+
+
+
+let dot v1 v2 =
+  if Vec.dim v1 <> Vec.dim v2 then
+    invalid_arg "Incompatible dimensions";
+  let local_dot =
+    Lacaml.D.dot (Vec.data v1) (Vec.data v2)
+  in
+  Mpi.reduce_float local_dot Mpi.Float_sum 0 Mpi.comm_world 
+
+
diff --git a/Parallel/Parallel.mli b/Parallel/Parallel.mli
index 1657722..a535afa 100644
--- a/Parallel/Parallel.mli
+++ b/Parallel/Parallel.mli
@@ -15,7 +15,7 @@ val barrier : unit -> unit
 (** {5 Vector operations} *)
 module Vec : sig
 
-  type t =
+  type t = private
   { 
     global_first : int ; (* Lower  index in the global array *)
     global_last  : int ; (* Higher index in the global array *)
@@ -26,7 +26,7 @@ module Vec : sig
 
   val pp : Format.formatter -> t -> unit
 
-  (** {6 Creation/conversion of vectors and dimension accessor} *)
+  (** {6 Creation/conversion of vectors} *)
 
   val create : int -> t
   (** [create n] @return a distributed vector with [n] rows (not initialized). *)
@@ -54,6 +54,27 @@ module Vec : sig
   val to_vec : t -> Lacaml.D.vec 
   (** [to_vec v] @return a Lacaml vector initialized from vector [v]. *)
 
+
+  (** {6 Accessors } *)
+
+  val dim : t -> int
+  (** [dim v] @return the dimension of the vector [v]. *)
+
+  val global_first : t -> int
+  (** [global_first v] @return the index of the first element of [v]. *)
+
+  val global_last  : t -> int
+  (** [global_last v] @return the index of the last element of [v]. *)
+
+  val local_first : t -> int
+  (** [local_first v] @return the index of the first element of the local piece of [v]. *)
+
+  val global_last  : t -> int
+  (** [local_last v] @return the index of the last element of the local piece of [v]. *)
+
+  val data : t -> Lacaml.D.vec
+  (** [data v] @return the local Lacaml vector in which the piece of the vector [v] is stored. *)
+
 end
 
 
@@ -77,10 +98,10 @@ end
 
 val gemm : Mat.t -> Mat.t -> Mat.t
 (* Distributed matrix-matrix product. The result is a distributed matrix. *)
+*)
 
 val dot : Vec.t -> Vec.t-> float
 (* Dot product between distributed vectors. *)
-*)
 
 
 
diff --git a/run_parallel.ml b/run_parallel.ml
index 54b67b0..fbe904f 100644
--- a/run_parallel.ml
+++ b/run_parallel.ml
@@ -5,11 +5,18 @@ let () =
 (*
 let v = Parallel.Vec.init 47 (fun i -> float_of_int i) in
 *)
-  let a = Array.init 6 (fun i -> float_of_int (i+1)) |> Lacaml.D.Vec.of_array in
-  let v = Parallel.Vec.of_vec a in
-  Format.printf "%a" Parallel.Vec.pp v;
+  let a = Array.init 41 (fun i -> float_of_int (i+1)) |> Lacaml.D.Vec.of_array in
+  let b = Array.init 41 (fun i -> float_of_int (3*i+1)) |> Lacaml.D.Vec.of_array in
+  let v1 = Parallel.Vec.of_vec a in
+  let v2 = Parallel.Vec.of_vec b in
+  let d1 = Parallel.dot v1 v2 in
+  let d2 = Lacaml.D.dot a b in
+  (*
   let w = Parallel.Vec.to_vec v in
+  Format.printf "%a" Parallel.Vec.pp v;
   if Parallel.master then
       Format.printf "@[%a@]@;" (Lacaml.Io.pp_lfvec ()) w;
+  *)
+  Printf.printf "%f %f\n" d1 d2;
   print_newline ();