The time constant, 
, can be measured by measuring the peak amplitudes of the oscillations. Recall that the time constant is given by Equation 3 of the Free Vib. Sys. Parameters:
(1)
Since both the positive and negative displacements follow the same curve, the magnitudes of all peak displacements can be fit to this exponential curve.
Use a least squares fit for exponential curves or the log decrement method
(plot the log of the displacement values vs. time) to determine the time constant. Note that in the log decrement method, the slope is -1/.
