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Table 1 Summary of quantities used in recurrence quantification analysis. Modified after Webber and Zbilut (2005): https://www.nsf.gov/pubs/2005/nsf05057/nmbs/nmbs.pdf

From: Nonlinear dynamical analysis of GNSS data: quantification, precursors and synchronisation

%recurrence, %REC Percentage of recurrent points falling within the specified radius, ε. \( \%\mathrm{REC}=100\frac{number\ of\ points\ in\ triangle}{\varepsilon \left(\varepsilon -1\right)/2} \)
%determinism, %DET Percentage of recurrent points forming diagonal line structures. This is a measure of determinism in the signal. \( \%\mathrm{DET}=100\frac{number\ of\ points\ in\ diagonal\ lines}{number\ of\ recurrent\ points} \)
Linemax, DMAX The length of the longest diagonal line in the plot (except main diagonal). DMAX = length of longest diagonal line in the recurrence plot
Entropy, ENT The Shannon information entropy of all diagonal line lengths over integer bins in a histogram. This is a measure of signal complexity with units bits/bin. ENT =  −  ∑ (Pbin)log2(Pbin)
Trend. TND A measure of system stationarity. \( \mathrm{TND}=1000\left(\begin{array}{l} slope\ of\% local\ recurrence\ \\ {}\kern2.25em vs. displacement\end{array}\right) \)
%laminarity, %LAM The percentage of recurrent points forming vertical line structures. \( \%\mathrm{LAM}=100\frac{number\ of\ points\ in\ vertical\ lines}{number\ of\ recurrent\ points} \)
VMAX The length of the longest vertical line in the plot. VMAX = length of longest vertical line in the recurrence plot
Trapping time, TT The average length of vertical line structures. TT = Average length of vertical lines ≥ parameter line