mineStepwise(data, essential.data=1,
method="efroymson", f.crit=2, intercept=TRUE,
subtract.means=FALSE, standardize=FALSE,
lags.in=6, lags.out=6, trend=FALSE, plot.=TRUE)
length(stepwise$rss)
by m and p respectively indicating if
a series is included for each element of rss.