Technical Details

This thorn supports three elliptic problem classes: LinFlat for a standard 3D cartesian Laplace operator, using the standard 7-point computational molecule. LinMetric for a Laplace operator derived from the metric, using 19-point stencil. LinConfMetric for a Laplace operator derived from the metric and a conformal factor, using a 19-point stencil. The code of the solvers differs for the classes and is explained in the following section.

In general, a stencil variable needs to be set for each of the direction relative to the central gridpoint. These variables are called ac, ae, aw, an, as, at, ab, ane, anw, ase, asw, ate, atw, abe, abw, atn, ats, abn, asb, where ``ac'' = a-central, ``t'' = top, ``b'' = bottom, ``n,s,w,e'' = north, south, west, east