print("\n".join(["Input mesh should have at least two materials and ", "two boundary attributes! (See schematic in ex17.cpp)\n"]))
sys.exit()
# 3. Refine the mesh to increase the resolution.
ref_levels = int(np.floor(np.log(5000./mesh.GetNE())/np.log(2.)/dim))
for x in range(ref_levels):
mesh.UniformRefinement();
# Since NURBS meshes do not support DG integrators, we convert them to
# regular polynomial mesh of the specified (solution) order.
if (mesh.NURBSext): mesh.SetCurvature(order)
# 4. Define a DG vector finite element space on the mesh. Here, we use
# Gauss-Lobatto nodal basis because it gives rise to a sparser matrix
# compared to the default Gauss-Legendre nodal basis.
fec = mfem.DG_FECollection(order, dim, mfem.BasisType.GaussLobatto)
fespace = mfem.FiniteElementSpace(mesh, fec, dim)
print('Number of finite element unknowns: '+ str(fespace.GetVSize()))
print('Assembling:')
# 5. In this example, the Dirichlet boundary conditions are defined by
# marking boundary attributes 1 and 2 in the marker Array 'dir_bdr'.
# These b.c. are imposed weakly, by adding the appropriate boundary
# integrators over the marked 'dir_bdr' to the bilinear and linear forms.
# With this DG formulation, there are no essential boundary conditions.
ess_tdof_list = intArray()
dir_bdr = intArray(mesh.bdr_attributes.Max())
dir_bdr.Assign(0)
dir_bdr[0] = 1 # boundary attribute 1 is Dirichlet
dir_bdr[1] = 1 # boundary attribute 2 is Dirichlet
print( "Unknown ODE solver type: " + str(ode_solver_type))
exit
# 4. Refine the mesh to increase the resolution. In this example we do
# 'ref_levels' of uniform refinement, where 'ref_levels' is a
# command-line parameter. If the mesh is of NURBS type, we convert it to
# a (piecewise-polynomial) high-order mesh.
for lev in range(ref_levels):
mesh.UniformRefinement();
if mesh.NURBSext:
mesh.SetCurvature(max(order, 1))
bb_min, bb_max = mesh.GetBoundingBox(max(order, 1));
# 5. Define the discontinuous DG finite element space of the given
# polynomial order on the refined mesh.
fec = mfem.DG_FECollection(order, dim)
fes = mfem.FiniteElementSpace(mesh, fec)
print("Number of unknowns: " + str(fes.GetVSize()))
#
# Define coefficient using VecotrPyCoefficient and PyCoefficient
# A user needs to define EvalValue method
#
class velocity_coeff(mfem.VectorPyCoefficient):
def EvalValue(self, x):
dim = len(x)
center = (bb_min + bb_max)/2.0
# map to the reference [-1,1] domain
X = 2 * (x - center) / (bb_max - bb_min)