how i can have gradient of a multivariate function like f(x,y) in a single function?

i define multivariate function f by syms order and wish have gradient f in especial point like x0 and i can not use from for loop

for example :

syms f(x,y)
f(x,y)=x^2+y^2,x0=(1,1)

i wish have

g=f'(x,y)

then

g(1,1)=[2,2]

Answer 1

[Brendan Hamm]

If you want this for a specific function you can just create the function directly:

>> g = @(x,y) [2*x,2*y];
>> g(1,1)
ans =
   2     2

Using the symbolic toolbox you can do the following:

syms x y
f =  x^2 + y^2;
g = gradient(f,[x y]);
subs(g,[x y],[1,1])

or if you really wanted this in a single function:

syms x y
f =  x^2 + y^2;
g = @(x0,y0) subs(gradient(f,[x y]),[x y],[x0 y0]);

[xosro]

tank you about your answer but my new problem is i do not know number of variables f because f is my input of my code then i can not write if x=[1;1]; g(x)