smooth(x, twiceit=T)
"rts" or
"cts") but not irregular (class
"its"). The length of each vector, column, or channel must be at least four. Missing values (
NA,
NaN or
Inf) are not accepted.
TRUE,
smooth performs twicing. Twicing is the process of smoothing, computing the residuals from the smooth, smoothing these, and then adding the two smoothed series together. By default,
twiceit=TRUE.
The object to be smoothed is coerced to a regular time series. The components of the smoothing process are as follows:
Running medians of length 4.
Tukey, J.W. (1977). Exploratory Data Analysis. Reading, Massachusetts: Addison-Wesley.
Velleman, P.F. and Hoaglin, D.C. (1981). Applications, Basics, and Computing of Exploratory Data Analysis. Boston: Duxbury.
McNeil, D.R. (1976). Interactive Data Analysis.
tsplot(hstart, lty=2) lines(smooth(hstart))