Seismosoft | Earthquake Engineering Solutions

I will appreciate your help on the following issue regarding A_95 parameter calculation.

I am wondering how SesimoSignal calculates A_95 parameter. As I tried to verify it with the following simple step-signal example:
a = 0 for t = [0,1)
a = 1g for t =[1,2)
a = 0 for t = 2
where "[" means ...