[Rd] ** operator

[Duncan Murdoch]

On 15/05/2008 7:07 AM, Tobias Verbeke wrote:
> Dear list,
> 
> I did not find any mentioning of the fact
> that the ** operator can be used as a
> synonym for the ^ operator.
> 
>  > 5 ** 2
> [1] 25
> 
> Searching of ** in the R Reference Index only leads
> to some examples in the mgcv documentation.
> 
> Equally ?"**" does not open the arithmetic
> operators help page, but produces
> 
>  > ?"**"
> No documentation for '**' in specified packages and libraries:
> you could try 'help.search("**")'
> 
> Is there any reason to this or am I overlooking
> something ?

It's fairly unlikely to go away, but it's an old undocumented feature, 
so use at your own risk.  There are lots of other undocumented features, 
but maybe no others at the lexical level.  Check out src/main/gram.y if 
you want to search for more at that level, and src/* if you want them at 
any level.

Duncan Murdoch

> 
> Many thanks in advance,
> Tobias
> 
>  > sessionInfo()
> R version 2.7.0 (2008-04-22)
> i486-pc-linux-gnu
> 
> locale:
> LC_CTYPE=en_US.UTF-8;LC_NUMERIC=C;LC_TIME=en_US.UTF-8;LC_COLLATE=en_US.UTF-8;LC_MONETARY=C;LC_MESSAGES=en_US.UTF-8;LC_PAPER=en_US.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US.UTF-8;LC_IDENTIFICATION=C
> 
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
> 
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