Search up to a maximum of the length of the time series
firstzero_ac(y, acfv = stats::acf(y, N - 1, plot = FALSE, na.action = na.pass))
the input time series
vector of autocorrelation, if exist, used to avoid repeated computation.
The first zero crossing of the autocorrelation function
B.D. Fulcher and N.S. Jones. hctsa: A computational framework for automated time-series phenotyping using massive feature extraction. Cell Systems 5, 527 (2017).
B.D. Fulcher, M.A. Little, N.S. Jones Highly comparative time-series analysis: the empirical structure of time series and their methods. J. Roy. Soc. Interface 10, 83 (2013).