Interior Galerkin equations are intended for specialized problems and are experimental and poorly tested. If Continuity warns you that such equations have been generated, you have most likely made a mistake in setting up the mesh. Geometries that use cubic Hermite interpolation store not only the spatial coordinates of each node, but the spatial derivatives as well. Thus, linear geometries will have 0 derivatives per coordinate, bicubic geometries will have 3 and tricubic geometries will have 8. For propagation problems, nodal coordinates must be entered in centimeters.
Nodal derivatives are with respect to the arc length of the corresponding element edge.
Not needed if all elements and nodes are defined using define nodes and define elements. Refine will sometimes issue a warning stating that SEs were not calculated. These warning can be disregarded. Time integration, Cardiac activation, Modified FitzHugh Nagumo equations or Beeler-Reueter, Finite element collocation, and nonlinear analysis. Not needed if problem is isotropic.