diff --git a/src/materials/material_linear_elastic4.hh b/src/materials/material_linear_elastic4.hh
index a051dcf..59a22af 100644
--- a/src/materials/material_linear_elastic4.hh
+++ b/src/materials/material_linear_elastic4.hh
@@ -1,212 +1,212 @@
 /**
  * @file   material_linear_elastic4.hh
  *
  * @author Richard Leute <richard.leute@imtek.uni-freiburg.de>
  *
  * @date   15 March 2018
  *
  * @brief linear elastic material with distribution of stiffness properties.
  *        In difference to material_linear_elastic3 two Lame constants are
  *        stored per pixel instead of the whole elastic matrix C.
  *        Uses the MaterialMuSpectre facilities to keep it simple.
  *
  * Copyright © 2018 Till Junge
  *
  * µSpectre 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, or (at
  * your option) any later version.
  *
  * µSpectre 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 GNU Emacs; see the file COPYING. If not, write to the
  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  * Boston, MA 02111-1307, USA.
  */
 
 #ifndef MATERIAL_LINEAR_ELASTIC_RANDOM_STIFFNESS_2_H
 #define MATERIAL_LINEAR_ELASTIC_RANDOM_STIFFNESS_2_H
 
 #include "materials/material_linear_elastic1.hh"
 #include "common/field.hh"
 #include "common/tensor_algebra.hh"
 
 #include <Eigen/Dense>
 
 namespace muSpectre {
 
   template <Dim_t DimS, Dim_t DimM>
   class MaterialLinearElastic4;
 
   /**
    * traits for objective linear elasticity with eigenstrain
    */
   template <Dim_t DimS, Dim_t DimM>
   struct MaterialMuSpectre_traits<MaterialLinearElastic4<DimS, DimM>>
   {
     //! global field collection
     using GFieldCollection_t = typename
       MaterialBase<DimS, DimM>::GFieldCollection_t;
 
     //! expected map type for strain fields
     using StrainMap_t = MatrixFieldMap<GFieldCollection_t, Real, DimM, DimM, true>;
     //! expected map type for stress fields
     using StressMap_t = MatrixFieldMap<GFieldCollection_t, Real, DimM, DimM>;
     //! expected map type for tangent stiffness fields
     using TangentMap_t = T4MatrixFieldMap<GFieldCollection_t, Real, DimM>;
 
     //! declare what type of strain measure your law takes as input
     constexpr static auto strain_measure{StrainMeasure::GreenLagrange};
     //! declare what type of stress measure your law yields as output
     constexpr static auto stress_measure{StressMeasure::PK2};
 
     //! local field_collections used for internals
     using LFieldColl_t = LocalFieldCollection<DimS>;
     //! local Lame constant type
     using LLameConstantMap_t = ScalarFieldMap<LFieldColl_t, Real, true>;
     //! elasticity without internal variables
     using InternalVariables = std::tuple<LLameConstantMap_t,
                                          LLameConstantMap_t>;
 
   };
 
   /**
    * implements objective linear elasticity with an eigenstrain per pixel
    */
   template <Dim_t DimS, Dim_t DimM>
   class MaterialLinearElastic4:
     public MaterialMuSpectre<MaterialLinearElastic4<DimS, DimM>, DimS, DimM>
   {
   public:
 
     //! base class
     using Parent = MaterialMuSpectre<MaterialLinearElastic4, DimS, DimM>;
     /**
      * type used to determine whether the
      * `muSpectre::MaterialMuSpectre::iterable_proxy` evaluate only
      * stresses or also tangent stiffnesses
      */
     using NeedTangent = typename Parent::NeedTangent;
     //! global field collection
 
     using Stiffness_t = Eigen::TensorFixedSize
       <Real, Eigen::Sizes<DimM, DimM, DimM, DimM>>;
 
     //! traits of this material
     using traits = MaterialMuSpectre_traits<MaterialLinearElastic4>;
 
     //! Type of container used for storing eigenstrain
     using InternalVariables = typename traits::InternalVariables;
 
     //! Hooke's law implementation
     using Hooke = typename
       MatTB::Hooke<DimM,
                    typename traits::StrainMap_t::reference,
                    typename traits::TangentMap_t::reference>;
 
     //! Default constructor
     MaterialLinearElastic4() = delete;
 
     //! Construct by name
     MaterialLinearElastic4(std::string name);
 
 
     //! Copy constructor
     MaterialLinearElastic4(const MaterialLinearElastic4 &other) = delete;
 
     //! Move constructor
     MaterialLinearElastic4(MaterialLinearElastic4 &&other) = delete;
 
     //! Destructor
     virtual ~MaterialLinearElastic4() = default;
 
     //! Copy assignment operator
     MaterialLinearElastic4& operator=(const MaterialLinearElastic4 &other) = delete;
 
     //! Move assignment operator
     MaterialLinearElastic4& operator=(MaterialLinearElastic4 &&other) = delete;
 
     /**
      * evaluates second Piola-Kirchhoff stress given the Green-Lagrange
      * strain (or Cauchy stress if called with a small strain tensor), the first
      * Lame constant (lambda) and the second Lame constant (shear modulus/mu).
      */
     template <class s_t>
     inline decltype(auto) evaluate_stress(s_t && E,
                                           const Real & lambda,
                                           const Real & mu);
 
     /**
      * evaluates both second Piola-Kirchhoff stress and stiffness given
      * the Green-Lagrange strain (or Cauchy stress and stiffness if
      * called with a small strain tensor), the first Lame constant (lambda) and
      * the second Lame constant (shear modulus/mu).
      */
     template <class s_t>
     inline decltype(auto) evaluate_stress_tangent(s_t &&  E,
                                                   const Real & lambda,
                                                   const Real & mu);
 
     /**
      * return the empty internals tuple
      */
     InternalVariables & get_internals() {
       return this->internal_variables;};
 
     /**
      * overload add_pixel to write into loacal stiffness tensor
      */
     void add_pixel(const Ccoord_t<DimS> & pixel) override final;
 
     /**
      * overload add_pixel to write into local stiffness tensor
      */
     void add_pixel(const Ccoord_t<DimS> & pixel,
-                   const Real & Poisson_ratio, const Real & Youngs_modulus);
+                   const Real & Youngs_modulus, const Real & Poisson_ratio);
 
   protected:
     //! storage for first Lame constant 'lambda'
     //! and second Lame constant(shear modulus) 'mu'
     using Field_t = MatrixField<LocalFieldCollection<DimS>, Real, oneD, oneD>;
     Field_t & lambda_field;
     Field_t & mu_field;
     //! tuple for iterable eigen_field
     InternalVariables internal_variables;
   private:
   };
 
   /* ---------------------------------------------------------------------- */
   template <Dim_t DimS, Dim_t DimM>
   template <class s_t>
   decltype(auto)
   MaterialLinearElastic4<DimS, DimM>::
   evaluate_stress(s_t && E, const Real & lambda, const Real & mu) {
     std::cout << "stress\n" <<
       Hooke::evaluate_stress(lambda, mu, std::forward<s_t>(E)) << std::endl;
     return Hooke::evaluate_stress(lambda, mu, std::forward<s_t>(E));
   }
 
   /* ---------------------------------------------------------------------- */
   template <Dim_t DimS, Dim_t DimM>
   template <class s_t>
   decltype(auto)
   MaterialLinearElastic4<DimS, DimM>::
   evaluate_stress_tangent(s_t && E, const Real & lambda,
 			  const Real & mu)
   {
     std::cout << "evaluate_stress_tangent; E:\n" << E << std::endl;
-    auto C = Hooke::compute_C_T4(lambda, mu);
+    T4Mat<Real, DimM> C = Hooke::compute_C_T4(lambda, mu);
     //auto stress{this->evaluate_stress(E)};
     //std::cout << "stress:\n" << stress << std::endl;
-    std::cout << "C:\n" << C << std::endl;
+    //std::cout << "C:\n" << C << std::endl;
     return std::make_tuple(this->evaluate_stress(std::forward<s_t>(E), lambda, mu), C);
   }
 
 
 }  // muSpectre
 
 #endif /* MATERIAL_LINEAR_ELASTIC_RANDOM_STIFFNESS_2_H */