Example

Suppose the temperature at each point of a metal plate is given by T(x,y)=Exp[x]Cos[y] + Exp[y]Cos[x].
In what direction does the temperature increase most rapidly at (0,0)? What is the rate of increase?


  T[x_,y_]:=Exp[x]*Cos[y] + Exp[y]*Cos[x]


  grad2[T][x,y]


  grad2[T][x,y]/.{x->0,y->0}

Answer:

Answer: ...

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