I need to define a kind of statistical function to retrieve a combination of
some set of values, but I don't know how to implement it in excel...maybe it
is possible using a macro...

The definition of the formula (CQC=complete quadratic combination) is given
by formula (16) and (17) here
http://www.ingegneriasismica.net/Tem...mbinazione.htm

or here
http://www.6dof.com/index.php?module...play&ceid= 64

TIA