diff --git a/tests/test_fractal.py b/tests/test_fractal.py
index 2f3fe86..9af42d0 100644
--- a/tests/test_fractal.py
+++ b/tests/test_fractal.py
@@ -1,102 +1,102 @@
 #!/usr/bin/python
 # -*- coding: utf-8 -*-
 ##*
  #
  # @author Guillaume Anciaux <guillaume.anciaux@epfl.ch>
  #
  # @section LICENSE
  #
  # Copyright (©)  2016 EPFL  (Ecole Polytechnique  Fédérale de
  # Lausanne)  Laboratory (LSMS  -  Laboratoire de  Simulation  en Mécanique  des
  # Solides)
  #
  # Tamaas is free  software: you can redistribute it and/or  modify it under the
  # terms  of the  GNU Lesser  General Public  License as  published by  the Free
  # Software Foundation, either version 3 of the License, or (at your option) any
  # later version.
  #
  # Tamaas 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  Lesser General  Public License  for more
  # details.
  #
  # You should  have received  a copy  of the GNU  Lesser General  Public License
  # along with Tamaas. If not, see <http://www.gnu.org/licenses/>.
  #
  #
 ################################################################
 
 import sys, imp
 
 from util_test import import_tamaas
 
 def main():
     tm = import_tamaas()
     #generate surface
     SG = tm.SurfaceGeneratorFilterFFT()
     SG.getGridSize().assign(512)
     SG.getHurst().assign(0.8)
     SG.getRMS().assign(1.);
     SG.getQ0().assign(4);
     SG.getQ1().assign(4);
     SG.getQ2().assign(32);
     SG.getRandomSeed().assign(156);
     SG.Init()
     a = SG.buildSurface()
 
     #compute and print surface statistics
     class Stats:
         def __getitem__(self,key):
             return self.__dict__[key]
 
 
     stats = Stats()
 
     stats.size = SG.getGridSize()
     stats.hurst = SG.getHurst().value()
     stats.rms = SG.getRMS()
     stats.k0 = SG.getQ0()
     stats.k1 = SG.getQ1().value()
     stats.k2 = SG.getQ2().value()
     stats.seed = SG.getRandomSeed()
     stats.rms_spectral = tm.SurfaceStatistics.computeSpectralStdev(a);
     stats.rms_slopes_spectral = tm.SurfaceStatistics.computeSpectralRMSSlope(a);
-    stats.rms_geometric = tm.SurfaceStatistics.computeStdev(SurfaceForPythonReal(a));
+    stats.rms_geometric = tm.SurfaceStatistics.computeStdev(tm.SurfaceForPythonReal(a));
     stats.rms_slopes_geometric = tm.SurfaceStatistics.computeRMSSlope(a);
     stats.moments = tm.SurfaceStatistics.computeMoments(a);
     stats.m0 = stats['rms_spectral']**2
     stats.m2 = stats.moments[0]
     stats.m4 = stats.moments[1]
     stats.alpha = stats['m0']*stats['m4']/(stats['m2']**2)
     stats.L = 1.
     stats.m0prime = tm.SurfaceStatistics.computeAnalyticFractalMoment(0,stats.k1,stats.k2,stats.hurst,1. , stats.L)
     stats.moment_A = stats.m0/stats.m0prime
     stats.analytic_m0 = tm.SurfaceStatistics.computeAnalyticFractalMoment(0,stats.k1,stats.k2,stats.hurst,stats.moment_A,stats.L);
     stats.analytic_m2 = tm.SurfaceStatistics.computeAnalyticFractalMoment(2,stats.k1,stats.k2,stats.hurst,stats.moment_A,stats.L);
     stats.analytic_m4 = tm.SurfaceStatistics.computeAnalyticFractalMoment(4,stats.k1,stats.k2,stats.hurst,stats.moment_A,stats.L);
     stats.analytic_alpha = stats.analytic_m0*stats.analytic_m4/(stats.analytic_m2*stats.analytic_m2);
 
     print """
     [N]                        {size}
     [rms]                      {rms}
     [rmsSpectral]              {rms_spectral}
     [rmsSlopeSpectral]         {rms_slopes_spectral}
     [rmsSlopeGeometric]        {rms_slopes_geometric}
     [Hurst]                    {hurst}
     [k1]                       {k1}
     [k2]                       {k2}
     [moment A]                 {moment_A}
     [m0]                       {m0}
     [analytic m0]              {analytic_m0}
     [m2]                       {m2}
     [analytic m2]              {analytic_m2}
     [m4]                       {m4}
     [analytic m4]              {analytic_m4}
     [alpha]                    {alpha}
     [analytic_alpha]           {analytic_alpha}
     [seed]                     {seed}
     """.format(**stats.__dict__)
     return 0
 
 if __name__ == "__main__":
     sys.exit(main())