DOLFIN

nodes coordinates of high order CG function space

Asked by Yi Jiang

Hi,

Does anyone know how to get a list of all nodes coordinates of high order CG function space. Say I have a 2nd order CG space like

mesh = UnitSquare(4,4)
V = FunctionSpace(mesh, 'CG', 2)

How do I get all the coordinates of the nodes (i.e., Degree of Freedom) of V? If V is linear CG space, mesh.coordinates() would give me those coordinates, is there a similar function for high order CG function space?

Thanks a lot.

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Garth Wells
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Best Garth Wells (garth-wells) said : 		#1

Look at

    GenericDofMap::tabulate_coordinates

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Yi Jiang (yijiang) said : 		#2

Thanks Garth,

Just for clarity and reference. I wrote the following script to do this task. It may be tedious, any comments are welcome.

mesh = UnitSquare(4,4)
V = FunctionSpace(mesh, 'CG', 1)

# Number of cells
NumCells = mesh.num_cells()

# Degree of freedoms
DOF = V.dofmap().global_dimension()

# Initialize nodes coordinates matrix
coor = np.zeros((DOF, 3))

# Evaluate nodes matrix by local-to-global map on each cells
for i in range(NumCells):

    # Current Cell
    C = Cell(mesh, i)

    # Coordinates of nodes in current cell
    cell_coor = V.dofmap().tabulate_coordinates(C)

    # Global indices of nodes in current cell, i.e., local-to-global maps
    nodes = V.dofmap().cell_dofs(i)

    # Evaluate global nodes coordinates matrix
    coor[nodes] = cell_coor

Finally coor is what I need.

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Yi Jiang (yijiang) said : 		#3

Thanks Garth Wells, that solved my question.