BTW, I have pushed a fix in mark/gamg-square. The parameter is now an integer. You will want at least 2. Inf should give you the old, pre January, semantics. Mark
On Thu, Apr 30, 2015 at 3:10 PM, Mark Adams <[email protected]> wrote: > > >> Yes, thanks, this is the change. If I switch back to using the square >> of the adjacency graph on all levels then I recover the previous >> behaviour. Mark, any comments? >> >> > The intent here is that you need to get faster coarsening on most > problems, especially not high order discretizations. After the first coarse > grid the number of non-zeros increases and this seems to be enough to > coarsen a good rate for the problems that I test: lowish order FE elements > (8 and maybe 27 node hexes). > > You have about 10 non-zeros per row. This is very low and squaring is not > even really enough. BTW, if you can add fake zeros to make a large stencil > and use a negative threshold value, GAMG will use that fake graph for > coarsening, that is, it will not drop the zeros from the coarsening graph. > > BTW, I hated making this change for this reason but made a mistake in > implementing this. I was always intending to do turn the squaring off > after the first level, but realized earlier this year that I was not > turning it off. > > Anyway, I would suggest that we turn the square graph argument into an > integer for the number of levels that you want. Zero would be like false, > one would be like true, and then you can add what you want. > > If there are no objections I will do this. It will break everyone that > uses this parameter but it is a better interface. > > Mark > > > >> Cheers, >> >> Lawrence >> >> -----BEGIN PGP SIGNATURE----- >> Version: GnuPG v1 >> >> iQEcBAEBAgAGBQJVP1ipAAoJECOc1kQ8PEYve1QH/3SChuuIZhDOoOOfxYnezCuC >> beXRvqrjem6SWMBIft67kvmAr9htGsiGg/vE+NRP9EwNu20kD+fYocJ+mBBcxFit >> 2FdUperqA8F9gys2wJ+TijEQx58ieBNJJyPmQRa1DOmKHmD/WWcCIBV5q+yML9kt >> B3z59ujUH1kJrmmpYmUk6aMUDAG0qU2KlVHX+p6zL1kV7ooGdYcKbiAbYdYrKO1l >> 6vNw65+51Oiyi2X/oAsnxeJeAvMN2ljaSYLZJ1RZgAndSLi6bcZPQZvtzwXfOLs9 >> C0qSPfXbd5O2DoenYnKzCS7t/kLnl0J3QimYex4tOSQxNQ7MtMG4CMNDmAIepUs= >> =OY/s >> -----END PGP SIGNATURE----- >> > >
