In this routine the unrefined tetrahedral mesh is catalogued. It consists of the folowing tasks:

- initialize kontet (take non-tet elements into account, close the gaps in the tet numbering)
- determine the nodes/tet relationship (kontet)
- calculate the circumscribed spheres of the tets (bc)
- calculate the center of gravity of the tets (cg)
- determine the tets/node relationship (ieln)
- catalogue the faces in ifac: nodes/face relationship
- determine the face equations (planfa)
- determine the faces/tet (ifatet)
- determine the tets/face (itetfa)

Notice that the tetrahedral elements are stored as if all of them were linear, ie. C3D4-elements. The only quadratic information of the unrefined mesh is stored in fields iedgext and ifacext, to be discussed below.

guido dhondt 2018-12-15