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?

bla · Accepted Answer · 2013-09-29 04:49:09Z

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.

answered Sep 29, 2013 at 4:49

bla

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Comments

shunyo · Accepted Answer · 2013-09-29 04:19:57Z

0

Try function out = f2(x(1),x(2))

answered Sep 29, 2013 at 4:19

shunyo

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Comments

cfcm · Accepted Answer · 2015-09-10 18:46:00Z

0

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

answered Sep 10, 2015 at 18:46

cfcm

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