copymask(OSubLattice<T2,OrderedSubset> d, const OLattice<T1>& mask, const OLattice<T2>& s1)
copymask(OLattice<T2>& dest, const OLattice<T1>& mask, const OLattice<T2>& s1)
copymask(OSubLattice<T2,OrderedSubset> d, const OLattice<T1>& mask, const OLattice<T2>& s1) {  OLattice<T2>& dest = d.field();  const OrderedSubset& s = d.subset();  for(int i=s.start(); i <= s.end(); ++i)     copymask(dest.elem(i), mask.elem(i), s1.elem(i));}