[Rd] option(expressions) and --max-ppsize

[Prof Brian Ripley]

On Mon, 14 Apr 2008, Tobias Verbeke wrote:

> Dear list,
>
> Is there an exact formula / safe rule of thumb that allows
> one to express the value of --max-ppsize as a function of
> the value of getOption("expressions") ?

There is none: it entirely depends on what you are doing.
But you would expect pp stack usage to be proportional to the number of 
expressions, the problem being what the ratio should be.

The ratio of the defaults was empirically determined, and should be a good 
guide.

However, if you find yourself increasing either then you probably want to 
rethink how you do the calculations in R.

> ?options tells "If you increase it [the expressions option],
> you may also want to start R with a larger protection stack".
>
> Motivation is to determine stack size of a Java vm used
> to launch R with a given --max-ppsize option.

R's expression limit is only vaguely related to its C stack usage
(assuming you mean 'embed R' not 'launch R' -- it is processes that get 
launched in the OS world I inhabit).

>
> Many thanks in advance,
> Tobias
>
> --
>
> Tobias Verbeke - Consultant
> Business & Decision Benelux
> Rue de la révolution 8
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>
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>
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-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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