the vector of estimated values for \(\mu(t)\) at t.y which is the vector of observation time points for the response function used in cv.hd.
beta
a list of length \(p\), the number of functional predictors. Its \(i\)-th element is a matrix of the estimated values of \(\beta_i(s,t)\) at the two-dimensional grid created by t.x.list[[i]] and t.y used in cv.hd.