[R] round() and negative digits

[Rolf Turner]

On 11/10/11 08:17, Michael Friendly wrote:
> On 10/9/2011 6:18 AM, Prof Brian Ripley wrote:
>>
>> Sometimes it is better not to document things than try to give precise
>> details which may get changed *and* there will be useRs who misread (and
>> maybe even file bug reports on their misreadings). The source is the
>> ultimate documentation.
>
> I can't agree with this less.  The source does the computation. The 
> documentation says how to use it and what it should do.  Corner cases
> can be trapped in code or mentioned in Notes.  But the source is
> only useful if you can easily find it and then can understand what it is
> doing, particularly for a .Primitive like round().
> The source is only the documentation of last resort.

I agree.  It seems to me that saying that the source is the ultimate 
documentation
is rather like (in pure mathematics) saying that all maths follows from the
Zermello-Fraenkel axioms plus the Axiom of Choice, so those axioms are 
all that we
need to tell anyone.

     cheers,

         Rolf Turner