diff --git a/Optimal_bounding_box/include/CGAL/Optimal_bounding_box/fitness_function.h b/Optimal_bounding_box/include/CGAL/Optimal_bounding_box/fitness_function.h
new file mode 100644
index 00000000000..87b4c662a44
--- /dev/null
+++ b/Optimal_bounding_box/include/CGAL/Optimal_bounding_box/fitness_function.h
@@ -0,0 +1,85 @@
+// Copyright (c) 2018 GeometryFactory (France).
+// All rights reserved.
+//
+// This file is part of CGAL (www.cgal.org).
+// 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.
+//
+// Licensees holding a valid commercial license may use this file in
+// accordance with the commercial license agreement provided with the software.
+//
+// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
+// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+//
+// $URL$
+// $Id$
+// SPDX-License-Identifier: GPL-3.0+
+//
+//
+// Author(s)     : Konstantinos Katrioplas
+
+#ifndef CGAL_FITNESS_FUNCTION_H
+#define CGAL_FITNESS_FUNCTION_H
+
+#include <CGAL/Bbox_3.h>
+#include <vector>
+
+
+namespace CGAL {
+namespace Optimal_bounding_box {
+
+template<typename Matrix>
+const double compute_fitness(Matrix& R, Matrix& data)
+{
+
+  // R: rotation matrix
+  CGAL_assertion(R.cols() == 3);
+  CGAL_assertion(R.rows() == 3);
+  // data: points
+  CGAL_assertion(data.cols() == 3);
+  CGAL_assertion(data.rows() >= 3);
+
+  CGAL_assertion(R.rows() == data.cols());
+
+  // rotate points
+  Matrix RT = R.transpose();
+  Matrix rotated_data = data * RT;
+  CGAL_assertion(rotated_data.cols() == data.cols());
+  CGAL_assertion(rotated_data.rows() == data.rows());
+
+  // AABB: take mins and maxs
+  double xmin = rotated_data.col(0).minCoeff();
+  double xmax = rotated_data.col(0).maxCoeff();
+  double ymin = rotated_data.col(1).minCoeff();
+  double ymax = rotated_data.col(1).maxCoeff();
+  double zmin = rotated_data.col(2).minCoeff();
+  double zmax = rotated_data.col(2).maxCoeff();
+
+  double x_dim = abs(xmax - xmin);
+  double y_dim = abs(ymax - ymin);
+  double z_dim = abs(zmax - zmin);
+
+  // volume
+  return (x_dim * y_dim * z_dim);
+
+}
+
+
+
+
+
+
+
+
+}} // end namespaces
+
+
+
+
+
+
+#endif //CGAL_FITNESS_FUNCTION_H
+
+
+
diff --git a/Optimal_bounding_box/include/CGAL/Optimal_bounding_box/linear_algebra.h b/Optimal_bounding_box/include/CGAL/Optimal_bounding_box/linear_algebra.h
index 8570964f2f1..83be8c79885 100644
--- a/Optimal_bounding_box/include/CGAL/Optimal_bounding_box/linear_algebra.h
+++ b/Optimal_bounding_box/include/CGAL/Optimal_bounding_box/linear_algebra.h
@@ -38,8 +38,7 @@ void qr_factorization(EigenMatrix& A, EigenMatrix& Q)
 }
 
 
-
-}}
+}} // end namespaces
 
 
 
diff --git a/Optimal_bounding_box/test/Optimal_bounding_box/test_linear_algebra_functions.cpp b/Optimal_bounding_box/test/Optimal_bounding_box/test_linear_algebra_functions.cpp
index 435c8a755da..27b00e3229f 100644
--- a/Optimal_bounding_box/test/Optimal_bounding_box/test_linear_algebra_functions.cpp
+++ b/Optimal_bounding_box/test/Optimal_bounding_box/test_linear_algebra_functions.cpp
@@ -2,6 +2,7 @@
 #include <CGAL/Surface_mesh.h>
 
 #include <CGAL/Optimal_bounding_box/linear_algebra.h>
+#include <CGAL/Optimal_bounding_box/fitness_function.h>
 
 #include <iostream>
 #include <fstream>
@@ -46,6 +47,26 @@ void test_qr_factorization()
 }
 
 
+void test_fitness_function()
+{
+  MatrixXf data_points(4, 3);
+  data_points << 0.866802, 0.740808, 0.895304,
+                 0.912651, 0.761565, 0.160330,
+                 0.093661, 0.892578, 0.737412,
+                 0.166461, 0.149912, 0.364944;
+
+  MatrixXf rotation(3, 3);
+  rotation << -0.809204, 0.124296, 0.574230,
+             -0.574694, 0.035719, -0.817589,
+             -0.122134, -0.991602, 0.042528;
+
+  double fitness = CGAL::Optimal_bounding_box::compute_fitness(rotation, data_points);
+  CGAL_assertion(assert_doubles(fitness, 0.58606, 1e-6));
+
+}
+
+
+
 
 
 
@@ -53,6 +74,7 @@ int main()
 {
 
   test_qr_factorization();
+  test_fitness_function();
 
   return 0;
 }