a scalar representing the embedding
dimension in past or future. Note that contrary to
'dimension = 1' in embed
, here
'max.lag = 1' will return a 2 column matrix (0 lag, 1
lag), and not just a 1 column matrix. Similarly, for
negative shift; e.g., 'max.lag = -2' returns 3 column
matrix with (0 lag, -1 lag, -2 lag).