The parameter \(\delta\) should be the first element in vector p. The degree of
the polynomial is then decided by the number of the remaining parameters.
##Load datadata("USunempr")
data("USrealgdp")
y <- diff(log(USrealgdp))
x <- window(diff(USunempr),start=1949)
t <- 1:length(y)
midas_r(y~t+fmls(x,11,12,nealmon),start=list(x=c(0,0,0)))