operator-(const ILattice<T1,N>& l)
operator-(const IScalar<T1>& l)
operator-(const ILattice<T1,N>& l){  typename UnaryReturn<ILattice<T1,N>, OpUnaryMinus>::Type_t  d;  for(int i=0; i < N; ++i)    d.elem(i) = -l.elem(i);  return d;}