[R] conv() example in R-exts
Prof Brian Ripley
ripley at stats.ox.ac.uk
Mon Nov 8 10:23:46 CET 2004
On Mon, 8 Nov 2004, Robin Hankin wrote:
> [I'm not sure if this is "intelligible to non-programmers" or not]
Not, I suspect: R-exts is not intended to be.
> R-exts (section 4.2) gives an example of the .C() function whose
> third argument is
> and urges the user to coerce all the arguments to the correct form
> (on pain of "hard-to-catch errors"
> which I now know to be very appropriate, if understated, phrasing).
> The length() function returns an integer, according to the helppage.
> So, why does the argument above use as.integer()?
Because things written on help pages can change.
There *is* a potential issue here, as 64-bit platforms could support
longer vectors than an R integer can represent. I suspect before too long
we will need a `size' type for lengths. Already object.size() has been
changed to return a double, not an integer, since people are created
objects of more than 2Gb in size.
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)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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