mainf — Infinite Moving average representation
[mainf_proxy]=mainf(ar,ma,nbterms)
ar= the ar part = a (px1) or (1xp) vector
ma = the ma part = a (qx1) or (1xq) vector
nbterms = # of terms developped (optional, default = 100)
mainf_proxy = the nbterms first terms of the Infinite Moving average representation
m=mainf([0.5 .2],[1 -0.3 -0.4],200) // Calculates the 200 first terms of the Infinite Moving AverageRepresentation of the ARMA process : // (1-0.5*L-0.2*L^2) xt= (1-0.3*L-0.4*L^2) et m=mainf([0.5 .2],[1 -0.3 -0.4]) // calculates the 200 first terms of the Infinite Moving Average Representation of the same ARMA process.