diff2D(f_):=diff2D(f,x); diff2D(f_,x_,n_):=ds(x=>topow(f),x,n); diff2D(f_,x_):=ds(x=>topow(f),x); diff2D(d(f_,x_,n_),x_):=ds(x=>topow(f),x,n); diff2D(d(f_,x_),x_):=ds(x=>topow(f),x); diff2D(f_ and f2_,x_,n_):=ds(x=>topow(f),x,n) and ds(x=>topow(f2),x,n); diff2D(f_ and f2_,x_):=ds(x=>topow(f),x) and ds(x=>topow(f2),x); diff2D(f_ and f2_):=ds(x=>topow(f),x) and ds(x=>topow(f2),x); diff2D(f_=g_,x_):=diff2D(f,x)=diff2D(g,x); diff2D(f_+g_,x_):=diff2D(f,x)+diff2D(g,x);