mscroggs
commented
1 month ago I've corrected it to say "second derivatives" rather than "Jacobian" for now as that corrects the error.
The DOF diagrams on DefElement aren't very good for elements with derivative evaluations involved, so I've opened https://github.com/mscroggs/symfem/issues/269 on Symfem (which is used to generate the diagrams) for this.
Mistake description Hi, on the Argyris page we can read: "On each vertex: point evaluations, point evaluations of derivatives in coordinate directions, and point evaluations of components of Jacobian On each edge: point evaluations of normal derivatives at midpoints" Which is misleading, if not incorrect. I believe a better description would be : "Value (3 DOFs), gradient (6 DOFs) and hessian (9 DOFs) at each vertex. Dot product of the gradient and the outward unit normal vector at each edge's midpoint (3 DOFs)."
We could argue that the drawing is not necessarily false, but I find it misleading too.
Additional context The description is clear on wikipedia although it is in french. It comes with a clear drawing too.