tk/Inhouse_lmm: correlation matrix is symetric

lib/toolbox/inhouse_lmm.ml

@@ -43,7 +43,10 @@ let index_correlations (t : Convergence_tree.u) cors =
 
 let matrix_of_correlations n cor_assoc =
   let mat = L.Mat.create n n in
-  List.iter cor_assoc ~f:(fun (i, j, c) -> mat.{i + 1, j + 1} <- c) ;
+  List.iter cor_assoc ~f:(fun (i, j, c) ->
+      mat.{i + 1, j + 1} <- c ;
+      mat.{j + 1, i + 1} <- c ;
+    ) ;
   mat
 
 let design_matrix ~m ~n ~aa_at_site (al : Alignment.t) =