On Thu, Aug 27, 2015 at 5:35 PM, Jed Brown <j...@jedbrown.org> wrote:
> Barry Smith <bsm...@mcs.anl.gov> writes: > > This is the default behavior if one just creates a PetscRandom and > uses it, so don't be going and setting seeds inside GAMG or Chebyshev. > > You're right (my mistake), but the consequences are dangerous if the > user is holding a PetscRandom across calls to GAMG (or anything that > creates new PetscRandom instances). The reason is that merely creating > a PetscRandom reseeds the global PRNG. (What moron thought a global > seed was a good idea?) Seems to me we should avoid drand48 always so we > don't disrupt the user's source of randomness (leading to really > confusing incorrect results). We could use the non-disastrous > drand48_r, but it's a GNU extension so we'd need an alternative anyway. > > If Matt changes "rander48" to the rand48_r (or erand48_r) interface, > then we'd be okay. This would also remove the internal variables that > Matt forget to make static. > I will make them local to the object, and we will all be fine then. Matt -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener
