[R] First Derivative of Data Matrix

[spencerg]

      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]
>