Evaluation of solution at a specific point

General
1

Hello,

In dolfinx, is the following code fragment from the Static condensation of linear elasticity example:

# Create bounding box for function evaluation
bb_tree = geometry.bb_tree(msh, 2)

# Check against standard table value
p = np.array([[48.0, 52.0, 0.0]], dtype=np.float64)
cell_candidates = geometry.compute_collisions_points(bb_tree, p)
cells = geometry.compute_colliding_cells(msh, cell_candidates, p).array

uc.x.scatter_forward()
if len(cells) > 0:
    value = uc.eval(p, cells[0])
    print(value[1])

the best way to find the value of a FEM solution (in this case uc, which is a function defined over some space V on the mesh msh) at a specified point (in this case p)? Is there a simpler way? I have seen that in fenics there was the more intuitively obvious uc(p).

Thanks in advance for any advice.

Peter.

2

See for instance

The reason for the core code in DOLFINx being explicit is that one should cache all of

if the mesh doesn’t move.

This has also been covered in

3

Thank you very much. It is all much clearer now.