From 224a87d42224c62542b6d820d7c5e582a6b31bca Mon Sep 17 00:00:00 2001
From: Anthony Scemama <scemama@irsamc.ups-tlse.fr>
Date: Wed, 17 Oct 2018 10:38:07 +0200
Subject: [PATCH] Distributed vector

---
 Parallel/Parallel.ml  | 22 ++++++++++++++++++++++
 Parallel/Parallel.mli |  5 +++--
 run_parallel.ml       |  8 ++++++--
 3 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/Parallel/Parallel.ml b/Parallel/Parallel.ml
index f3d4f13..7f2db2e 100644
--- a/Parallel/Parallel.ml
+++ b/Parallel/Parallel.ml
@@ -15,6 +15,7 @@ let rank =
   assert (result >= 0);
   result
 
+let master = rank = 0
 
 let barrier () =
   Mpi.barrier Mpi.comm_world
@@ -90,5 +91,26 @@ module Vec = struct
     let () = Mpi.scatter_float_array a a_local 0 Mpi.comm_world in
     { result with data = Lacaml.D.Vec.of_array a_local }
 
+
+  let to_array vec = 
+    let final_size = vec.global_last - vec.global_first + 1 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
+    let () = Mpi.gather_float_array data buffer 0 Mpi.comm_world in
+    if final_size = buffer_size then
+      buffer
+    else
+      Array.init final_size (fun i -> buffer.(i))
+
+      
+  let of_vec a =
+    Lacaml.D.Vec.to_array a
+    |> of_array
+
+
+  let to_vec v =
+    to_array v
+    |> Lacaml.D.Vec.of_array
     
 end
diff --git a/Parallel/Parallel.mli b/Parallel/Parallel.mli
index 1de2e00..1657722 100644
--- a/Parallel/Parallel.mli
+++ b/Parallel/Parallel.mli
@@ -6,6 +6,9 @@ val size : int
 val rank : Mpi.rank
 (** Rank of the current distributed processe. *)
 
+val master : bool
+(** True if [rank = 0]. *)
+
 val barrier : unit -> unit
 (** Wait for all processes to reach this point. *)
 
@@ -42,7 +45,6 @@ module Vec : sig
   val of_array : float array -> t
   (** [of_array ar] @return a distributed vector initialized from array [ar]. *)
 
-(*
   val to_array : t -> float array
   (** [to_array v] @return an array initialized from vector [v]. *)
 
@@ -51,7 +53,6 @@ module Vec : sig
 
   val to_vec : t -> Lacaml.D.vec 
   (** [to_vec v] @return a Lacaml vector initialized from vector [v]. *)
-*)
 
 end
 
diff --git a/run_parallel.ml b/run_parallel.ml
index c475045..54b67b0 100644
--- a/run_parallel.ml
+++ b/run_parallel.ml
@@ -5,7 +5,11 @@ let () =
 (*
 let v = Parallel.Vec.init 47 (fun i -> float_of_int i) in
 *)
-  let a = Array.init 47 (fun i -> float_of_int (i+1)) in
-  let v = Parallel.Vec.of_array a 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 w = Parallel.Vec.to_vec v in
+  if Parallel.master then
+      Format.printf "@[%a@]@;" (Lacaml.Io.pp_lfvec ()) w;
+  print_newline ();