On Thu, Aug 27, 2015 at 3:11 PM, Barry Smith <bsm...@mcs.anl.gov> wrote:
> > > On Aug 27, 2015, at 1:58 PM, Jed Brown <j...@jedbrown.org> wrote: > > > > Mark Adams <mfad...@lbl.gov> writes: > > > >> Ah, you're right. > >> > >> Would you consider this a decent hash? > >> > >> PetscScalar v = ((PetscScalar)((79943*idx)%6871) - 3435.)/3435. + > >> ((PetscScalar)((7919*idx)%829) - 415.)/415.; > > > > Still bullshit. Plot this and you'll see that there are lots of > > patterns and it's just not very rough at all. Try grid sizes of 48, 59, > > 64, 74, 75, 80, 85 to name a few. (I looped over some grids in Octave.) > And orthogonal to the high modes of say the Laplacian I assume, > > This is a fools errand. > > >> I thought drand48 has been taken off the table because of Windows. If > it's > >> not I can use that. > > > > Use drand48, > > Don't use drand48 directly; use PetscRandom. Matt promised to fix up > PetscRandom to use it by default and work on all systems so all you need to > do is use PetscRandom everywhere. > > Barry > > > it's very simple. > > > > http://pubs.opengroup.org/onlinepubs/007908799/xsh/drand48.html > >
