handles for functions of several variables

Im trying to make function handles that make it possible to calculate functions with different values for x1 and x2, but I cannot make it work. Please help?

(This is not the entire code, and it is split into two files)

syms x1 x2
x0 = [-1; -1];
f = @f_function;
J = @J_function;
 
X = NewtonsMethod(f, J, x0, lim, N)

function f = f_function(x)
    f=[(x1*x2-2);
    ((x1.^4/4) + (x2.^3/3) -1)];
end
 
function J = J_function(x)
    J = jacobian(f, [x1,x2]);
end

File:NewtonsMethod

    xn = x0; % initial estimate
    n = 1; % iteration number
    fn = f(xn); % save calculation    

    iterate = norm(fn,Inf) > tol;
    while iterate
        xn = xn - J(xn)\fn;
        n = n+1;
        X(:,n) = xn;

        fn = f(xn);

Answer 1

[Walter Roberson]

syms x1 x2
x0 = [-1; -1];
fsym = f_function(x1,x2);
f = matlabFunction(fsym, 'vars', {[x1, x2]})

f = function_handle with value:
    @(in1)[in1(:,1).*in1(:,2)-2.0;in1(:,1).^4./4.0+in1(:,2).^3./3.0-1.0]

J = matlabFunction(jacobian(fsym), 'vars', {[x1, x2]})

J = function_handle with value:
    @(in1)reshape([in1(:,2),in1(:,1).^3,in1(:,1),in1(:,2).^2],[2,2])

 
X = NewtonsMethod(f, J, x0, lim, N)

Unrecognized function or variable 'lim'.

function f = f_function(x1,x2)
    f=[(x1*x2-2);
    ((x1.^4/4) + (x2.^3/3) -1)];
end

[Stina Ravdna Lorås]

Thank you! :)

Answer 2

[Jan]

Do you get an error message?

What is x1 and x2 in your functions "f_function" and "J_function"? Do you mean: x(1) and x(2) ?

Be careful with the unary minus in vectors:

    f=[(x1*x2-2);
    ((x1.^4/4) + (x2.^3/3) -1)];
    %                      ^   

This can confuse the parser. See:

[1 1]    % [1, -1]
[1 -1]   % [1, -1]
[1 - 1]  % [2]

[Stina Ravdna Lorås]

x1 and x2 is x(1) and x(2) = x.

I used parathesis to avoid the misunderstanding between row or function.

I've now changed my handles into this:

f = @(x)[(x(1)*x(2)-2);

((x(1).^4/4)+(x(2).^3/3)-1)];

J = @(x)jacobian(f, x);

But it is still wrong...

[Stina Ravdna Lorås]

Thank you for answering though! :)