follow bug27, 1. "U_dag_minus = _torch.roll(U_dag_mu, shifts=1, dims=ward)", the "ward" is changed to 0123 from -1-2-3-4 in bug27, now I add "ward = lattice.wards[ward_key]" below "ward_key = lattice.ward_keys[ward]"; 2. pyqcu::dslash::operator::matvec_* test pass. orz