      static double mp_vargmaxabs(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = (double)(&vec.maxabs() - vec.data()));
      }
      static double mp_vargmaxabs(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = (double)(&vec.maxabs() - vec.data()));
      }