Hi > I made some design matrix X(in linear regression model) > > I there any method to normalize X? You can normalize a matrix column-wise like this: # m is a matrix apply(m, 2, function(x) x / max(x) ) Or normalize row-wise like this: t(apply(m, 1, function(x) x / max(x) )) I'm sure there are more elegant ways to do it but those work for me. Michael