Difficulty implementing simulated annealing algorithm

While there are exaplanations for this (see the following link), I couldn't figure out exactly how to implement it:

https://www.mathworks.com/help/gads/examples/minimization-using-simulated-annealing-algorithm.html

This is the code that I am typing, based on the info in the link:

type simple_objective
function y = simple_objective(x)
x1 = x(1);
x2 = x(2);
y = (4-2.1.*x1.^2+x1.^4./3).*x1.^2+x1.*x2+(-4+4.*x2.^2).*x2.^2;
ObjectiveFunction = @simple_objective;
x0 = [0.5 0.5];   % Starting point
rng default % For reproducibility
[x,fval,exitFlag,output] = simulannealbnd(ObjectiveFunction,x0)

I don't understand what exactly is wrong with that code (I keep getting an error). I am very new to MATLAB and would appreciate any help!

Answer 1

[Stephan]

rng default % For reproducibility
x0 = [0.5 0.5];   % Starting point
[x,y,flag,output] = simulannealbnd(@simple_objective,x0)

function y = simple_objective(x)
x1 = x(1);
x2 = x(2);
y = (4-2.1.*x1.^2+x1.^4./3).*x1.^2+x1.*x2+(-4+4.*x2.^2).*x2.^2;
end

[Abbi Hashem]

I still get the following error:

Undefined function or variable 'x'.

Is there something else to add to the code to make this error go away?

[Stephan]

did you exactly copy my code? it runs for me with result:

Optimization terminated: change in best function value less than options.FunctionTolerance.

x =

   -0.0896    0.7130


y =

   -1.0316


flag =

     1


output = 

  struct with fields:

     iterations: 2948
      funccount: 2971
        message: 'Optimization terminated: change in best function value less than options.FunctionTolerance.'
       rngstate: [1×1 struct]
    problemtype: 'unconstrained'
    temperature: [2×1 double]
      totaltime: 1.1943

[Abbi Hashem]

I was typing something wrong, it just did, thank you so much!