What's the difference between R^2 and r?

Hello, can someone explain please, what's exactly the meaning of R_squared? The one which is defined in the link below - r_squared

and R(1,2) is you can get if you do:

R = corrcoef(A,B);

A,B - 2 vectors.

[Rik]

This doesn't look like a Matlab question to me. Have you read the doc for corrcoef?

Answer 1

[ANKUR KUMAR]

The value which you get for corrcoef (gives output a matrix and further extracting second column from first row) or from corr2 (if you have specified tool box) is the correlation coefficient. The same answer you can get manually too by doing this calculation.

function [ P ] = pcorr( a,b )
%pcorr gives the Pearson Correlation Coefficient between the two vector of
%equal dimensions

if length(a)~=length(b)
   error('Dimension of both must be equal') 
end
n=(numel(a)*nansum(a.*b))-(nansum(a)*nansum(b));
d1=(numel(a)*nansum(a.^2))-((nansum(a))^2);
d2=(numel(b)*nansum(b.^2))-((nansum(b))^2);
P=n/(sqrt(d1*d2));
end

The above value can be positive or negative.

Squared R (R^2) is just the square of r.