Very small difference between tabulate_dof_coordinates and geometry.x

[dokken]

This has also been discussed to some length at:

Can I improve the accurace of node coordinates

Yes, the mesh.geometry.x is more accurate when the nodes of the mesh coincide with the degrees of freedom, which is only the case in iso-parametric FEM methods. As I have already stated, there will always be floating error in tabulation (usually of somewhere around sqrt(floating_precision)), which you cannot avoid. It rarely causes any problems as long as you use double-precision floats. Yes and no, this depends on your function space. What happens is that the function is evaluated at the i…