matlab find min value without constraint

Question

I am new to matlab.
I am going to find the minimun value give the function: x(1)^2 - 2*x(1)*x(2) + 6*x(1) + x(2)^2 - 6*x(2)

I am trying to write the matlab code without using the anonymous function, but I am stuck here now.

Here is my code:

function minFun()
    res = fminsearch(@f2, [0,0]);

    function out = f2([x(1) x(2)])
        out = x(1)^2 - 2*x(1)*x(2) + 6*x(1) + x(2)^2 - 6*x(2);
    end
end

But it mentions that here is syntax error in function out = f2([x(1) x(2)]) . How should I fix that?

Answer 1

If I understand you correctly you have 2 files. In your f2.m file you should use

function out = f2(x)
    out = x(1)^2 - 2*x(1)*x(2) + 6*x(1) + x(2)^2 - 6*x(2);

The input x is already a vector.

If there is only one file then this should be the syntax:

function minFun()
    res = fminsearch(@f2, [0,0])

function out = f2(x)
    out = x(1)^2 - 2*x(1)*x(2) + 6*x(1) + x(2)^2 - 6*x(2);

note that I left res without ; so you can see the output of the fminsearch .

Answer 2

尝试功能out = f2(x(1),x(2))

Answer 3

Note that matlab Anonymous functions are called with the @ operator, so your question is a little confusing, as your code try to use it.

function out = f2([x(1) x(2)])

This line is incorrect, you should use a variable as function argument x .

If you do not want to use Anonymous function you should have a f2.m file in your working directory or in matlab path, as the other answer says.

function out = f2(x)
out = x(1)^2 - 2*x(1)*x(2) + 6*x(1) + x(2)^2 - 6*x(2);

Then you reference the function with a string:

function minFun()
res = fminsearch('f2', [0,0]);
end