--- a/INDEX	Sat Jul 12 17:28:08 2014 +0200
+++ b/INDEX	Sun Jul 13 19:25:03 2014 +0200
@@ -23,6 +23,7 @@
   JacobianForm
   Functional
 Creation of the discretized problem
+  linear_algebra_backend
   assemble
   assemble_system
 Post processing

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/inst/linear_algebra_backend.m	Sun Jul 13 19:25:03 2014 +0200
@@ -0,0 +1,40 @@
+## Copyright (C) 2014 Eugenio Gianniti <eugenio.gianniti@mail.polimi.it>
+##
+## This program is free software; you can redistribute it and/or modify it under
+## the terms of the GNU General Public License as published by the Free Software
+## Foundation; either version 3 of the License, or (at your option) any later
+## version.
+##
+## This program is distributed in the hope that it will be useful, but WITHOUT
+## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+## details.
+##
+## You should have received a copy of the GNU General Public License along with
+## this program; if not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} @var{val} = linear_algebra_backend ()
+## @deftypefnx {Function File} @var{old_val} = linear_algebra_backend (@var{new_val})
+##
+## Query or set the internal variable that specifies the linear algebra back-end
+## to use when assembling systems, matrices or vectors. It defaults to "uBLAS".
+##
+## @end deftypefn
+
+function output = linear_algebra_backend (varargin)
+  persistent backend = "uBLAS";
+  persistent opts = {"uBLAS"};
+
+  if (nargin > 1)
+    print_usage ();
+  else
+    output = backend;
+    if (nargin == 1)
+      input = validatestring (varargin{1}, opts, "linear_algebra_backend",
+                              "new_val");
+      backend = input;
+    endif
+  endif
+
+endfunction
\ No newline at end of file

--- a/src/femfenics_factory.cc	Sat Jul 12 17:28:08 2014 +0200
+++ b/src/femfenics_factory.cc	Sun Jul 13 19:25:03 2014 +0200
@@ -17,11 +17,25 @@
 
 #include "femfenics_factory.h"
 #include "uBLAS_factory.h"
+#include <octave/parse.h>
 
 femfenics_base_factory const&
 femfenics_factory::factory (void) const
   {
-    //FIXME: Since just one backend has its interface implemented, this method
-    //       doesn't check which one to provide, yet
+    std::string backend = linear_algebra_backend ();
+    /* Here go the returns for other back-ends
+    if (backend == "PETSc")
+      return PETSc_factory::instance (); ...
+    */
+
+    // Default back-end
     return uBLAS_factory::instance ();
+  }
+
+std::string
+femfenics_factory::linear_algebra_backend (void) const
+  {
+    octave_value_list ovl = feval ("linear_algebra_backend");
+    std::string retval = ovl(0).string_value ();
+    return retval;
   }
\ No newline at end of file

--- a/src/femfenics_factory.h	Sat Jul 12 17:28:08 2014 +0200
+++ b/src/femfenics_factory.h	Sun Jul 13 19:25:03 2014 +0200
@@ -19,6 +19,7 @@
 #define __FEMFENICS_FACTORY__
 
 #include "femfenics_base_factory.h"
+#include <string>
 
 class femfenics_factory : public femfenics_base_factory
 {
@@ -39,11 +40,7 @@
   femfenics_factory (femfenics_factory const&);
   femfenics_factory operator = (femfenics_factory const&);
 
-
-  //FIXME: just one backend implemented
-  inline char const * linear_algebra_backend (void) const
-    { return "uBLAS"; }
-
+  std::string linear_algebra_backend (void) const;
   femfenics_base_factory const& factory (void) const;
 };