gaussian(d,s);
random(r1,s); random(r2,s);  const int istart = s.start() >> INNER_LOG; const int iend   = s.end()   >> INNER_LOG;  for(int i=istart; i <= iend; ++i) fill_gaussian(d.elem(i), r1.elem(i), r2.elem(i));
void gaussian(const OSubLattice<T,S>& dd){  OLattice<T>& d = const_cast<OSubLattice<T,S>&>(dd).field();  const S& s = dd.subset();  gaussian(d,s);}