evaluating the value of the gradient at some point.

I have

syms x1 x2
f=x1^2+4*x2^2-8*x1-16*x2

f =

x1^2 - 8*x1 + 4*x2^2 - 16*x2

grad_f=gradient(f)

grad_f =

    2*x1 - 8
   8*x2 - 16

Now, I would like to evaluate the value of the gradient of f at some point, let say (x1,x2)=(1,0).

What should I do?

Answer 1

[Walter Roberson]

subs(grad_f, {x1, x2}, {1, 0})

You will likely want to double() the result of the subs()

[Del]

Thanks, but what do you mean by "likely want to double() the result of the subs()"?

[Walter Roberson]

double(subs(grad_f, {x1, x2}, {1, 0}))

[Bishwesvar Pratap Singh]

Thank you