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.; I thought drand48 has been taken off the table because of Windows. If it's not I can use that. Mark On Thu, Aug 27, 2015 at 12:48 PM, Jed Brown <j...@jedbrown.org> wrote: > Mark Adams <mfad...@lbl.gov> writes: > > > My hash function is: > > > > PetscScalar v = ((PetscScalar)((PETSC_HASH_FACT*idx)%100) - > > 49.5)/50.0; > > ierr = VecSetValues(bb, 1, &idx, &v, > > INSERT_VALUES);CHKERRQ(ierr); > > > > > > include/petscctable.h:#define PETSC_HASH_FACT 79943 > > Still grid-aligned stripes on a 100xN grid. Please stop it with these > bullshit ad-hoc hash functions. Either use a decent hash function or > drand48. >
