dune-localfunctions  2.8.0
raviartthomas03dlocalinterpolation.hh
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1 // -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
2 // vi: set et ts=4 sw=2 sts=2:
3 #ifndef DUNE_LOCALFUNCTIONS_RAVIARTTHOMAS_RAVIARTTHOMAS03D_RAVIARTTHOMAS03DLOCALINTERPOLATION_HH
4 #define DUNE_LOCALFUNCTIONS_RAVIARTTHOMAS_RAVIARTTHOMAS03D_RAVIARTTHOMAS03DLOCALINTERPOLATION_HH
5 
6 #include <cmath>
7 #include <array>
8 #include <bitset>
9 #include <vector>
11 
12 namespace Dune
13 {
14  template<class LB>
16  {
17  public:
18 
20  RT03DLocalInterpolation (std::bitset<4> s = 0)
21  {
22  using std::sqrt;
23  for (std::size_t i=0; i<sign_.size(); i++)
24  sign_[i] = (s[i]) ? -1.0 : 1.0;
25 
26  m_[0] = {1/3.0, 1/3.0, 0.0};
27  m_[1] = {1/3.0, 0.0, 1/3.0};
28  m_[2] = { 0.0, 1/3.0, 1/3.0};
29  m_[3] = {1/3.0, 1/3.0, 1/3.0};
30  n_[0] = { 0.0, 0.0, -1.0};
31  n_[1] = { 0.0, -1.0, 0.0};
32  n_[2] = { -1.0, 0.0, 0.0};
33  n_[3] = {1.0/sqrt(3.0), 1.0/sqrt(3.0), 1.0/sqrt(3.0)};
34  c_[0] = sqrt(2.0);
35  c_[1] = sqrt(2.0);
36  c_[2] = sqrt(2.0);
37  c_[3] = sqrt(2.0)/sqrt(3.0);
38  }
39 
40  template<typename F, typename C>
41  void interpolate (const F& ff, std::vector<C>& out) const
42  {
43  // f gives v*outer normal at a point on the face!
44  auto&& f = Impl::makeFunctionWithCallOperator<typename LB::Traits::DomainType>(ff);
45 
46  out.resize(4);
47 
48  for (int i=0; i<4; i++)
49  {
50  auto y = f(m_[i]);
51  out[i] = (y[0]*n_[i][0]+y[1]*n_[i][1]+y[2]*n_[i][2])*sign_[i]/c_[i];
52  }
53  }
54 
55  private:
56  // Face orientations
57  std::array<typename LB::Traits::RangeFieldType,4> sign_;
58  // Face midpoints of the reference tetrahedron
59  std::array<typename LB::Traits::DomainType,4> m_;
60  // Unit outer normals of the reference tetrahedron
61  std::array<typename LB::Traits::DomainType,4> n_;
62  // Inverse triangle face area
63  std::array<typename LB::Traits::RangeFieldType,4> c_;
64  };
65 }
66 
67 #endif
Definition: bdfmcube.hh:16
Definition: raviartthomas03dlocalinterpolation.hh:16
void interpolate(const F &ff, std::vector< C > &out) const
Definition: raviartthomas03dlocalinterpolation.hh:41
RT03DLocalInterpolation(std::bitset< 4 > s=0)
Constructor with given set of face orientations.
Definition: raviartthomas03dlocalinterpolation.hh:20