Table 1.

Summary of parameter bounds for the single and double exponential models. Direction is defined as positive (+ve) or negative (−ve) depending on the direction from which the symmetry series approaches its final value.

Model (Parameters)	Direction	Overshoot	Bounds
Single (a; b; c)	+ve	–	[0, 2];  [−ln(2), 0]; [−1, 1]
	−ve	–	[−2, 0]; [$-ln$(2), 0]; [−1, 1]
Double ($a_s$; $b_s$; $a_f$; $b_f$; c)	+ve	No	[0, 1];  [−ln(2), 0]; [0, 1];  [−ln(2), 0]; [−1, 1]
		Yes	[−1, 0]; [−ln(2), 0]; [0, 1];  [−ln(2), 0]; [−1, 1]
	−ve	No	[−1, 0]; [−ln(2), 0]; [−1, 0]; [−ln(2), 0]; [−1, 1]
		Yes	[0, 1];  [−ln(2), 0]; [−1, 0]; [−ln(2), 0]; [−1, 1]