[R] open source and R

[(Ted Harding)]

On 14-Nov-05 Prof Brian Ripley wrote:
> On Sun, 13 Nov 2005 Ted.Harding at nessie.mcc.ac.uk wrote:
> 
> [...]
> 
>> There is one aspect though where R users are in the cold when
>> it comes to C and FORTAN. If you want to understand the function
>> 'eigen', say, then you can "?eigen" to learn about its usage.
>> You can enter "eigen" to see the R code, and indeed that is
>> not too imcomprehensible. But then you find
>>
>>  .Fortran("ch", n, n, xr, xi, values = dbl.n,
>>           !only.values, vectors = xr, ivectors = xi, dbl.n,
>>           dbl.n, double(2 * n), ierr = integer(1),
>>           PACKAGE = "base")
>>
>> and similar for "rs", "cg" and "rg". Where's the help for
>> these? Nowhere obvious! In fact you have to go to the source
>> code, locate the FORTRAN routines, and study these, hoping
>> that enough helpful comments have been included to steer
>> your study. So it is a much more formidable task, especially
>> if you are having to learn the language at the same time.
> 
> That is an unfair comment.  The help page for eigen explains what 
> routines are used and gives you references to books describing them.
> So the help _is_ in the most obvious place.

Apologies for misleading wording. This was not meant as a criticism
of R in any way, but as an illustration of the theme that, sooner
or later, you "drop through the floor" of what R can provide in
the way of explicit explanation. So, while R's help is indeed helpful
in this case in indicating an orientation for your travels in that
outside world, "out in the cold" as it were, users are then on
their own as far as R is concerned. This is of course inevitable,
and the comment was intended as part of the general response to
Robert that if you want to study how R does things you are led
to study how other software, on which R depends, does things.

Best wishes,
Ted.


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Date: 14-Nov-05                                       Time: 08:55:35
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