[R] Cross-correlation -- help.search()

[Martin Maechler]

>>>>> "Sven" == Sven Garbade <garbade at psy.uni-muenchen.de> writes:

    Sven> Kaspar Pflugshaupt wrote:
    >> 
    >> On 17.4.2002 16:55 Uhr, Sven Garbade wrote:
    >> 
    >> > I want to recalculate an analysis found in a paper. An empirical time
    >> > series (velocities, altogether 241 data values) were cross-correlated
    >> > with an invertited cosine function (200 milliseconds duration).
    >> > Following the authors the resulting values should offer some advantages:
    >> > being independent of gain and peak latency differences between single
    >> > trials and preserving the temporal aspect of the modulation. Is there a
    >> > function to calculate cross-correlations in R? I think cor() is ot the
    >> > right one.
    >> 
    >> You need the function ccf() in library(ts).

    Sven> Thanks, but I'm wondering why the R search engine found nothing
    Sven> appropriate for the keyword "cross-correlation".

Because, unfortunately it only looks at the 
\title{}, \name{}, \alias{}, and \keyword{} entries, but *NOT* the
\description{} one.

I think we should consider changing this eventually. Including
the \description{} would blow up the search database by more
than a factor of two probably, but since the introduction of
help.search() computers have more than quadrupled in
performance. 

((and I have also changed the title of library/ts/man/acf.Rd
  such that  help.search("cross.*corr")  will find the proper
  help page, namely the one of "acf()" which also contains
  "ccf()"
))

Martin Maechler <maechler at stat.math.ethz.ch>	http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum  LEO C16	Leonhardstr. 27
ETH (Federal Inst. Technology)	8092 Zurich	SWITZERLAND
phone: x-41-1-632-3408		fax: ...-1228			<><
Martin Maechler <maechler at stat.math.ethz.ch>	http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum  LEO C16	Leonhardstr. 27
ETH (Federal Inst. Technology)	8092 Zurich	SWITZERLAND
phone: x-41-1-632-3408		fax: ...-1228			<><
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