a = where(Layout::latticeCoordinate(mu) == slice, LatticeFermion(sitefield), zero);
LatticeFermion tmp; tmp = sitefield;  a = where(Layout::latticeCoordinate(mu) == slice, tmp, LatticeFermion(zero));
void walfil(LatticeFermion& a, int slice, int mu, int color_index, int spin_index){  START_CODE("walfil");  if (color_index >= Nc || color_index < 0)    QDP_error_exit("invalid color index", color_index);  if (spin_index >= Ns || spin_index < 0)    QDP_error_exit("invalid spin index", spin_index);  // Write ONE to all field  Real one = 1;  Complex sitecomp = cmplx(one,0);  ColorVector sitecolor = zero;  Fermion sitefield = zero;  pokeSpin(sitefield,	   pokeColor(sitecolor,sitecomp,color_index),	   spin_index);  // Narrow the context to the desired slice.  a = where(Layout::latticeCoordinate(mu) == slice,	    LatticeFermion(sitefield), zero);  END_CODE("color_index");}