creating a function getting the graident and passing variables to them

Hi !

I am trying to creat a function that I can both use to pass values and compute the gradient of that function.

I tried both these :

but the for the first I cant pass values and the 2nd the gradient function in matlab does not work

syms x1 x2
f= 100*(x2-x1^2)^2 + (1+x1)^2;
gr= gradient(f)

%%%%%% other way 

syms x1 x2 
f=@(x1,x2) 100*(x2-x1^2)^2 + (1+x1)^2;
gr= gradient(f)

[Geoff Hayes]

Nora - please clarify what you mean by but the for the first I cant pass values and the 2nd the gradient function in matlab does not work. What do you mean by this? Are you observing errors? If so, what are they?

[Nora Khaled]

yes there were some error when I try to do f(2,3) for example and the second one had error related to the gradient function not accepting a function was created using f=@(x,y).

but it currntly works using what was suggested in the answers.

thank you !

Answer 1

[Alex Mcaulley]

Is this that you want?

syms f(x1,x2)
f(x1,x2)= 100*(x2-x1^2)^2 + (1+x1)^2;
gr(x1,x2) = gradient(f,[x1,x2])

Then you can compute

f(0,0)
gr(0,0)

[Nora Khaled]

Thank you this work.