Why does globalRefine() sometimes segfault for AlbertaGrid<3>?
This is a known issue with ALBERTA. The segfault you experience is a actually a stack overflow during the recursive bisection algorithm. When trying to refine an element, ALBERTA tries to use a prescribed refinement edge. It tries to refine all elements that share this edge (called a refinement patch) at the same time. But this edge need not be a refinement edge for the other elements in the patch. Therefore, ALBERTA tries to recursively refine such an element before refining the current patch. This way, one can run into cycles. While ALBERTA can ensure that the recursive bisection terminates in 2d, no such algorithm is known in 3d. One has to rely on heuristics to solve this problem. A simple idea is to select the longest edge for refinement on the macro grid. If this edge is unique, it makes the algorithm terminate in 2d. In 3d, this works unless an element is refined more that once. By default, the GridFactory for AlbertaGrid does not modify the grid. There are two reasons for this:
