MATLAB: I wrote a function for a math formula, may I ask you please check the code

Question

Hey all,

For my research, I needed to calculate some formula, So I searched everywhere, including Matlab file exchange and find nothing about the formula that I needed. Hence I decided to write a function for them and use them in my code. This is the very first time for me to write a function and also the first time to write a math formula. May I please ask you to check if where I do wrong?

Here is the formula:

And here is the function I wrote (I considered O as x and M as y):

function index_agreement = indexagreement(x,y) 
%In the name of God - This function calculate
%   Detailed explanation goes here
A = sum((y-x).^2);
B = abs(y - (mean(x)));
C = x - abs((mean(x)));
D = sum((B+C).^2);
index_agreement = 1 - (D);
end

Description: I run this function successfully, but I'm not sure about results because I believe they are not reasonable.

I want to thank you all.

Best Regards

Answer 1

Assuming vertical bars mean absolute value and not modulus...

You got C wrong. Try

C = abs(x - abs((mean(x)));

then you need

index_agreement = 1 - abs(A / D);

There may be more errors, but I stopped looking once I found those errors.