Example

What about T(x,y)=x^2+y^2? (Same question as above.)

In[170]:=

  T[x_,y_]:=x^2+y^2

In[171]:=

  grad2[T][x,y]

Out[171]=

  {2 x, 2 y}

Answer:

Answer: ...

Up to Rate of Change and Gradient