Hello, When using the function [y,s]=filter(b,a,x,s) in MATLAB and b=1 and a=[0.5 0.5] we have a filter with infinite impulse response. Why does MATLAB operate with the convention that the length of the transient s is max(length(b),length(a))-1 ? Is there something magical about this ? In theory the response is infinite, so the length of the transient could also be 10, 20 or 100 or something else.... What's the explanation for this choice? Thanks in advance...