density(kernel = "cosine") .. the `wrong cosine' ..

[Prof Brian D Ripley]

On Wed, 1 Dec 1999, Martin Maechler wrote:

> Problem:
> 
>  - An average user knowing some statistics literature will most probably
>    assume that a "cosine" kernel means the one in the literature, 
>    *NOT* the one we have in R now.

Or they have know what is in S (or what V&R say it is). (Yes, we knew of
the discrepancy, so defined it.)

> Proposition / Possibilities / RFC [= Request For Comments] :
> 
>  - We CHANGE the behavior of  density(* , kernel="cosine")
>    to use the cosine from the litterature.

I am against that. S compatibility and all that.

>  - provide the current "cosine" as  kernel = "smoothcosine"
>    {I'd like to keep the possibility of 1-initial-letter abbreviation}

OK, or

3) As it is confusing and never used(?), drop it altogether.

> Enhancement (easy, I'll do that):
> 
>   - We further provide both
>     Epanechnikov and "quartic" aka "biweight" additionally
>     in any case.

You may find it hard to get agreement on what those are (the problem
being the scale factors).

-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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