function delta2 = met_regularity(yB,yBA)
%
% function delta = met_regualrity(yB,yBA)
% yB  [l x 1] is a vector of dependent variables, measured
% yBA [l x 1] is a vector of dependent variables, obtained as yBA = XB * wA, 
% where:
% XB [l x n] is a matrix of independed variables, subset B and
% wA [n x 1] is a weights' vectors, obtained using yA, XA, subset A.

delta2 = sumsqr(yB - yBA);
return