diff.fts.R
`diff.fts` <- function (x, lag = 1, differences = 1, ...)
{
if (class(x)[1] == "fts"|class(x)[1] == "sfts"){
x$y <- t(diff(t(x$y), lag, differences, ...))
return(x)
}
else{
stop("object is not a functional time series or a sliced functional time series")
}
}