Line data    Source code

       1              : /*
       2              :  * Copyright (c) 2014:  G-CSC, Goethe University Frankfurt
       3              :  * Author: Sebastian Reiter
       4              :  * 
       5              :  * This file is part of UG4.
       6              :  * 
       7              :  * UG4 is free software: you can redistribute it and/or modify it under the
       8              :  * terms of the GNU Lesser General Public License version 3 (as published by the
       9              :  * Free Software Foundation) with the following additional attribution
      10              :  * requirements (according to LGPL/GPL v3 §7):
      11              :  * 
      12              :  * (1) The following notice must be displayed in the Appropriate Legal Notices
      13              :  * of covered and combined works: "Based on UG4 (www.ug4.org/license)".
      14              :  * 
      15              :  * (2) The following notice must be displayed at a prominent place in the
      16              :  * terminal output of covered works: "Based on UG4 (www.ug4.org/license)".
      17              :  * 
      18              :  * (3) The following bibliography is recommended for citation and must be
      19              :  * preserved in all covered files:
      20              :  * "Reiter, S., Vogel, A., Heppner, I., Rupp, M., and Wittum, G. A massively
      21              :  *   parallel geometric multigrid solver on hierarchically distributed grids.
      22              :  *   Computing and visualization in science 16, 4 (2013), 151-164"
      23              :  * "Vogel, A., Reiter, S., Rupp, M., Nägel, A., and Wittum, G. UG4 -- a novel
      24              :  *   flexible software system for simulating pde based models on high performance
      25              :  *   computers. Computing and visualization in science 16, 4 (2013), 165-179"
      26              :  * 
      27              :  * This program is distributed in the hope that it will be useful,
      28              :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      29              :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
      30              :  * GNU Lesser General Public License for more details.
      31              :  */
      32              : 
      33              : #ifndef __H__UG_DISC__GRADIENT_EVALUATORS__
      34              : #define __H__UG_DISC__GRADIENT_EVALUATORS__
      35              : 
      36              : #include "grid_function.h"
      37              : #include "common/util/provider.h"
      38              : #include "lib_disc/common/geometry_util.h"
      39              : #include "lib_disc/reference_element/reference_element_util.h"
      40              : #include "lib_disc/reference_element/reference_mapping_provider.h"
      41              : #include "lib_disc/local_finite_element/local_finite_element_provider.h"
      42              : 
      43              : namespace ug{
      44              : 
      45              : /**     Provides a function to evaluate the gradient of a given grid function efficiently
      46              :  * in each element.*/
      47              : template <class TFunction>
      48              : class GradientEvaluator_LagrangeP1{
      49              :         public:
      50              :                 static const int dim = TFunction::dim;
      51              :                 typedef MathVector<dim>                                           vector_t;
      52              :                 typedef typename TFunction::element_type        elem_t;
      53              : 
      54            0 :                 GradientEvaluator_LagrangeP1(TFunction* u, size_t fct)  :
      55            0 :                         m_pu(u),
      56            0 :                         m_aaPos(u->domain()->position_accessor()),
      57            0 :                         m_fct(fct)
      58            0 :                 {}
      59              : 
      60            0 :                 vector_t evaluate(elem_t* elem)
      61              :                 {
      62            0 :                         TFunction& u = *m_pu;
      63              : 
      64              :                 //      reference object type
      65            0 :                         ReferenceObjectID roid = elem->reference_object_id();
      66              : 
      67              :                 //      get trial space
      68              :                         const LocalShapeFunctionSet<dim>& lsfs =
      69            0 :                                         LocalFiniteElementProvider::get<dim>(roid, LFEID(LFEID::LAGRANGE, dim, 1));
      70              : 
      71              :                 //      create a reference mapping
      72              :                         DimReferenceMapping<dim, dim>& map
      73            0 :                                 = ReferenceMappingProvider::get<dim, dim>(roid);
      74              : 
      75              :                 //      get local Mid Point
      76            0 :                         vector_t localIP = ReferenceElementCenter<dim>(roid);
      77              : 
      78              :                 //      number of shape functions
      79            0 :                         const size_t numSH = lsfs.num_sh();
      80            0 :                         vLocalGrad.resize(numSH);
      81            0 :                         vGlobalGrad.resize(numSH);
      82              : 
      83              :                 //      evaluate reference gradient at local midpoint
      84            0 :                         lsfs.grads(&vLocalGrad[0], localIP);
      85              : 
      86              :                 //      get corners of element
      87            0 :                         CollectCornerCoordinates(vCorner, *elem, m_aaPos);
      88              : 
      89              :                 //      update mapping
      90            0 :                         map.update(&vCorner[0]);
      91              : 
      92              :                 //      compute jacobian
      93            0 :                         map.jacobian_transposed_inverse(JTInv, localIP);
      94              : 
      95              :                 //      compute gradient at mid point by summing contributions of all shape fct
      96              :                         vector_t elemGrad;
      97              :                         VecSet(elemGrad, 0.0);
      98            0 :                         for(size_t sh = 0 ; sh < numSH; ++sh)
      99              :                         {
     100              :                         //      get global Gradient
     101              :                                 MatVecMult(vGlobalGrad[sh], JTInv, vLocalGrad[sh]);
     102              : 
     103              :                         //      get vertex
     104            0 :                                 Vertex* vert = elem->vertex(sh);
     105              : 
     106              :                         //      get of of vertex
     107              :                                 std::vector<DoFIndex> ind;
     108            0 :                                 u.inner_dof_indices(vert, m_fct, ind);
     109              : 
     110              :                         //      scale global gradient
     111              :                                 vGlobalGrad[sh] *= DoFRef(u, ind[0]);
     112              : 
     113              :                         //      sum up
     114              :                                 elemGrad += vGlobalGrad[sh];
     115              :                         }
     116            0 :                         return elemGrad;
     117              :                 }
     118              :         private:
     119              :                 TFunction* m_pu;
     120              :                 typename TFunction::domain_type::position_accessor_type m_aaPos;
     121              :                 size_t m_fct;
     122              :         //      the following members are declared here so that they can be efficiently reused
     123              :                 MathMatrix<dim, dim> JTInv;
     124              :                 std::vector<vector_t > vLocalGrad;
     125              :                 std::vector<vector_t > vGlobalGrad;
     126              :                 std::vector<vector_t > vCorner;
     127              : };
     128              : 
     129              : }//     end of namespace
     130              : #endif