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I have problem writing a matlab function

Asked by Cantor Set on 19 Oct 2019 at 14:01
Latest activity Answered by Image Analyst
on 19 Oct 2019 at 15:47
I want to write this function in matrix form.
The function is
I defined the vector as:
Then what is wrong with my code?
function [ ObjVall ] = objfun2( phen)
%UNTITLED Summary of this function goes here
% Detailed explanation goes here
x=(5/pi)*phen(1:end,1)-6;
y=phen(1:end,2) - (5.1/(4*pi^2)).*(phen(1:end,1).^2 +x);
z=10*(1 - (1/(8*pi))*cos(phen(1:end,1)));
ObjVall=(y).^2 + z +10;
end

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3 Answers

Answer by the cyclist
on 19 Oct 2019 at 14:28
Edited by the cyclist
on 19 Oct 2019 at 14:34

The coefficient
(5.1/(4*pi^2))
is multiplying the term you have called x, which is not correct.
It might have been easier to debug if you define
x1 = phen(:,1);
x2 = phen(:,2);
inside your function, which will make your MATLAB expression look more like the math equation.

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Answer by Sedi Ghan
on 19 Oct 2019 at 14:37

I don't know where is wrong in your code. However, I write your formula as follows and it works.
function [ ObjVall ] = objfun2( phen)
%UNTITLED Summary of this function goes here
% Detailed explanation goes here
ObjVall= (phen(:,2) - (5.1/(4*pi^2))*phen(:,1).^2 + (5/pi)*phen(:,1)-6 ).^2+...
+10*(1-(1/8*pi)*cos(phen(:,1))) + 10;
end
When phen is an N by 2 matrix, the output is an N by 1 array.

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Answer by Image Analyst
on 19 Oct 2019 at 15:47

Make sure x1 and x2 are column vectors (Nx1), NOT row vectors (1xN).

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