[Rd] Documentation for taper in spec.taper (PR#8871)

stein at galton.uchicago.edu stein at galton.uchicago.edu
Wed May 17 22:17:23 CEST 2006

Full_Name: Michael Stein
Version: Version 2.1.1
OS: linux
Submission from: (NULL) (

The documentation for spec.taper says

      p: The total proportion to be tapered, either a scalar or a
          vector of the length of the number of series.


     The cosine-bell taper is applied to the first and last 'p[i]/2'
     observations of time series 'x[, i]'.

However, the program actually applies the taper to the first and last p[i]
observations, so 2 * p is the total proportion to be tapered.

The documentation for spec.pgram says

   taper: proportion of data to taper.  A split cosine bell taper is
          applied to this proportion of the data at the beginning and
          end of the series.

The second statement is correct, but this means that the proportion of the data

that is tapered is 2 * taper, not taper.  This documentation could easily lead
users getting twice as much tapering as they think they are getting.

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