Merge branch 'feature/add-unit-tests' into 'master'

assembleGlobalBasisTransferMatrix: add more unit testing

See merge request !72

dune/fufem/test/assembletransferoperatortest.cc

@@ -136,6 +136,41 @@ bool testPowerBasis(const GW0& gw0, const GW1& gw1)
 }
 
 
+
+
+template<int order0, int order1, class GW0, class GW1>
+bool testOrder(const GW0& gw0, const GW1& gw1)
+{
+  // our test funcion for interpolation
+  auto f = [](const auto& x)
+  {
+    FieldVector<double,3> y;
+    y = 1.;
+    for( auto xs : x )
+    {
+      y[0] += std::sin(xs);
+      y[1] += 2*xs +5.;
+      y[2] += 3*xs*xs;
+    }
+    return y;
+  };
+
+  using namespace Functions::BasisFactory;
+
+  auto lagrange0 = makeBasis(gw0, power<3>(lagrange<order0>(),blockedInterleaved()));
+  auto lagrange1 = makeBasis(gw1, power<3>(lagrange<order1>(),blockedInterleaved()));
+
+  BCRSMatrix<FieldMatrix<double,3,3>> matrix;
+  BlockVector<FieldVector<double,3>> coeffs0, coeffs1;
+
+  const auto diff = checkInterpolation(matrix, f, lagrange0, coeffs0, lagrange1, coeffs1);
+
+  std::cout << " test interpolation P" << order0 << " -> P" << order1 << " : error = " << diff << std::endl;
+
+  return diff < 1e-12;
+}
+
+
 template<int order, class GW0, class GW1>
 bool testRaviartThomas(const GW0& gw0, const GW1& gw1)
 {
@@ -251,6 +286,14 @@ bool checkTransferMatrix(const GW0& gw0, const GW1& gw1)
   if constexpr ( GW0::dimension==2 )
     passed = passed and testRaviartThomas<0>(gw0,gw1);
 
+    // 2D: check lagrange interpolation for different orders on the same grid
+  if constexpr ( GW0::dimension < 3 )
+  {
+    passed = passed and testOrder<1,2>(gw1,gw1);
+    passed = passed and testOrder<2,3>(gw1,gw1);
+    passed = passed and testOrder<1,3>(gw1,gw1);
+  }
+
   return passed;
 }