X = A1*(exp(-alpha*t)).*cos(wd*t)+ A2*(exp(-alpha*t)).*sin(wd*t) is the equation of the damped curve with parameters as t=0:0.000050:0.1; A1 = 12.87701558; A2 = -12.70012814; alpha = 67.91641; wd = 4770.680551
The equation of the enveloping curve is I = Io * exp(-67.91641*t) where Io is the peak values of the damped curve
I am attaching the image of damped curve as well as its enveloping curve through peak points.