Defining my objective function using vector of variables for lsqnonlin

I wanna use lsqnonlin for estimating vector of variables of length 6

function F = myfun()
global X      % regression matrix of (nx6)
global Y      % output vector (nx1)
F = Y - ( w(1)*X(:,1) + w(2)*X(:,2) + w(3)*X(:,3) + w(4)*X(:,4) + w(5)*X(:,5) + w(6)*X(:,6) );
end

How can I dynamically define my function to adapt with any change in the number of variables (m) when the regression matrix dimesions (nxm) is changed. as follow

F = Y - ( w(1)*X(:,1) + w(2)*X(:,2) + w(3)*X(:,3) + .. + w(m)*X(:,m) );