I have a number of signals whose ACF may or may not cross the zero line. Whether roots exist or not is a piece of useful information for me. Likewise, if any root exists, I'd like to know its lag value. Unluckily R function ACF does not seem to provide such information. I wonder whether someone can come up with some suggestions ... maybe there is some other function that yields the regular ACF plus more ... Otherwise, I would appreciate some literature reference or just any advice that can help. Thank you so much. Maura tutti i telefonini TIM! [[alternative HTML version deleted]]