I am a bit confused with the following dxd(u) – based upon which mesh the derivative is calculated?
Th=movemesh (Th, …);
u=u; // Is this just an interpolation?
dxd(u); // second
u[ ] = uo[ ]; // is this a Larangian update?
Can I say the first dxd(u) is computed using the old mesh, and the second dxd(u) uses the new mesh, but the derivatives are the same? both of which are different to the third dxd(u)?