Best to ask in the mailing list. The main developer arre there too. They will for sure give a reason or tell us a meshing parameter we need tu use to archive this. I understand what you mean but it is difficault do explain to others.HarryvL wrote: ↑Tue Apr 02, 2019 6:11 amIt’s simpler than that @Jee-Bee. The structure of the global stiffness matrix is S[3*i,3*j], which is 0 except when i and j are nodes that belong to the same element. So it is essential to number the nodes such that the difference between node numbers within one element is minimal. The smaller the bandwidth=3*max(j-i) the better for storage and speed. I am surprised that GMSH doesn’t optimize node numbering in such away.
Well, I managed to reduce the bandwidth by a factor of 5 with reverse Cuthill McKee, but I doesn’t make any difference for the solution time . The search continues.HarryvL wrote: ↑Mon Apr 01, 2019 7:47 pmUrrrrr, I just calculated the number of degrees of freedom (DOF) and the band width (BW) for the plate with hole and find they are almost equal: DOF = 2990 and BW = 2970. Clearly the node numbering is hugely inefficient. I don't understand why GMSH doesn't produce a more efficient numbering. Anyway, this explains why use of sparsity doesn't matter and give hope that pre-conditioning (reverse Cuthill McKee) will help a lot.