"stag" - A DM object representing a “staggered grid” or a structured cell complex. See the manual chapter on DMStag.
This implementation parallels the
DMDA implementation in many ways, but allows degrees of freedom
to be associated with all “strata” in a logically-rectangular grid.
Each stratum can be characterized by the dimension of the entities (“points”, to borrow the
terminology), from 0- to 3-dimensional.
In some cases this numbering is used directly, for example with
To allow easier reading and to some extent more similar code between different-dimensional implementations
of the same problem, we associate canonical names for each type of point, for each dimension of DMStag.
1-dimensional DMStag objects have vertices (0D) and elements (1D).
2-dimensional DMStag objects have vertices (0D), faces (1D), and elements (2D).
3-dimensional DMStag objects have vertices (0D), edges (1D), faces (2D), and elements (3D).