Evaluating a derivative at a point in Mathematica

[Rasalhague]

If I define a function, such as

f[x_, y_] := {-2 x + 2 x^2, -3 x + y + 3 x^2}

I can compute the derivative with

D[f[x, y], {{x, y}}]

but what is the syntax for evaluating this derivative at a point?

 

[Bill Simpson]

Maybe something like this?

In[1]:= f[x_, y_] := {-2 x + 2 x^2, -3 x + y + 3 x^2};
df = D[f[x, y], {{x, y}}]

Out[2]= {{-2 + 4 x, 0}, {-3 + 6 x, 1}}

In[3]:= df /. {x -> 1, y -> 2}

Out[3]= {{2, 0}, {3, 1}}

or this

In[4]:= D[f[x, y], {{x, y}}] /. {x -> 1, y -> 2}

Out[4]= {{2, 0}, {3, 1}}

 

[Rasalhague]

Great, thanks, Bill!