short version of LinearFit.m from MOLI which includes only ARM

matlab/LinearFit_s.m

+function [gamma,fit] = LinearFit_s(time,Na00abs)
+  % LinearFit computes the growth rate and frequency from the time evolution of Napj
+  % - adapted from MOLI (B.J. Frei)
+  %
+
+    % ... amplitude ratio method
+
+    % We compute the mean of the growth rate over a time window [0.8*Trun,]
+    Trun = time(end);
+
+    lowerbound_timewindow = 0.8*Trun;
+    [~,begin_timewindow_ind] = min(abs(time - lowerbound_timewindow));
+
+    Na00absshifted = circshift(Na00abs,-1);    % ... shift by -1 the time position 
+    gammaoft = log(Na00absshifted(1:end-1)./Na00abs(1:end-1))./(diff(time)); % ... evaluate growth rate
+
+    % Get gamma
+    gamma = mean(gammaoft(end-begin_timewindow_ind:end)); % ... take the mean of gamma over the time window
+
+    % Return gamma(t) for amplitude ratio method
+    fit.gammaoft = gammaoft;
+
+
+    % Return fit
+    fit.t_fit_min = lowerbound_timewindow;
+    fit.t_fit_max = Trun;
+
+end % ... end function