Lafler-Kinman1 is an effective method to analyze Cepheids or RR Lyrae time series in search for periodic signals. It is a string-length method : it folds the observation data on a series of trial periods, and at each trial period it calculates the sum of the lengths of line segments joining successive points (the string-length). Minima in the plot of string-length versus trial frequency (Period Window) indicate possible periods.  

The Lafler-Kinman dialog box is similar to the Lomb-Scargle dialog box. Prominent periods of the Period Window appear as valleys.


(1) Lafler J., Kinman T.D., An RR Lyrae Star Survey with the Lick 20-INCH Astrograph II. The Calculation of RR Lyrae Periods by Electronic Computer, Astrophysical Journal Supplement, vol 11, p. 216, 1965.