However, estimating derivatives from differencing data amplifies
minor errors. Less noisy estimates can be obtained by first smoothing
and then differentiating the smooth. The "fda" package provides
substantial facilities for this.
Hope this helps.
Spencer Graves
David Winsemius wrote:
delta(index) is identically 1, so taking first differences is all that
is needed. If the dtatframe's name is df then:
df$dacflong_dx <- c(NA, diff(acflong)) # the slash would not be a
legal character in a variable name unless you jumped through some
hoops that appear entirely without value
If you want to get rid of the first line of df then
df[-1]
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