TODO: test computeMedoids + filter
#		#R-equivalent, requiring a matrix (thus potentially breaking "fit-in-memory" hope)
#		mat_meds = medoids[,]
#		mi = rep(NA,nb_series)
#		for (i in 1:nb_series)
#			mi[i] <- which.min( rowSums( sweep(mat_meds, 2, ref_series[i,], '-')^2 ) )
#		rm(mat_meds); gc()