diff --git a/Modules/DiffusionImaging/mitkDiffusionFunctionCollection.cpp b/Modules/DiffusionImaging/mitkDiffusionFunctionCollection.cpp
index 2d55483cec..4db8e9705a 100644
--- a/Modules/DiffusionImaging/mitkDiffusionFunctionCollection.cpp
+++ b/Modules/DiffusionImaging/mitkDiffusionFunctionCollection.cpp
@@ -1,104 +1,105 @@
 /*===================================================================
 
 The Medical Imaging Interaction Toolkit (MITK)
 
 Copyright (c) German Cancer Research Center,
 Division of Medical and Biological Informatics.
 All rights reserved.
 
 This software is distributed WITHOUT ANY WARRANTY; without
 even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.
 
 See LICENSE.txt or http://www.mitk.org for details.
 
 ===================================================================*/
 
 #include "mitkDiffusionFunctionCollection.h"
 #include <math.h>
 #include "mitkVector.h"
 
 // for Windows
 #ifndef M_PI
 #define M_PI  3.14159265358979323846
+#endif
 
 // Namespace ::SH
 #include <boost/math/special_functions/legendre.hpp>
 #include <boost/math/special_functions/spherical_harmonic.hpp>
 #include <boost/version.hpp>
 
 // Namespace ::vnl_function
 //#include "vnl/vnl_vector.h"
 
 //------------------------- SH-function ------------------------------------
 
 double mitk::sh::factorial(int number) {
     if(number <= 1) return 1;
     double result = 1.0;
     for(int i=1; i<=number; i++)
         result *= i;
     return result;
 }
 
 void mitk::sh::Cart2Sph(double x, double y, double z, double *cart)
 {
     double phi, th, rad;
     rad = sqrt(x*x+y*y+z*z);
     if( rad < mitk::eps )
     {
         th = M_PI/2;
         phi = M_PI/2;
     }
     else
     {
         th = acos(z/rad);
         phi = atan2(y, x);
     }
     cart[0] = phi;
     cart[1] = th;
     cart[2] = rad;
 }
 
 double mitk::sh::legendre0(int l)
 {
     if( l%2 != 0 )
     {
         return 0;
     }
     else
     {
         double prod1 = 1.0;
         for(int i=1;i<l;i+=2) prod1 *= i;
         double prod2 = 1.0;
         for(int i=2;i<=l;i+=2) prod2 *= i;
         return pow(-1.0,l/2.0)*(prod1/prod2);
     }
 }
 
 
 double mitk::sh::Yj(int m, int l, double theta, double phi)
 {
   if (m<0)
       return sqrt(2.0)*::boost::math::spherical_harmonic_r(l, -m, theta, phi);
   else if (m==0)
       return ::boost::math::spherical_harmonic_r(l, m, theta, phi);
   else
       return pow(-1.0,m)*sqrt(2.0)*::boost::math::spherical_harmonic_i(l, m, theta, phi);
 
   return 0;
 }
 
 
 //------------------------- VNL-function ------------------------------------
 
 
 template<class CurrentValue, class WntValue>
 vnl_vector<WntValue> mitk::vnl_function::element_cast (vnl_vector<CurrentValue> const& v1)
 {
   vnl_vector<WntValue> result(v1.size());
 
   for(int i = 0 ; i < v1.size(); i++)
        result[i] = static_cast<WntValue>(v1[i]);
 
   return result;
 }