[Rd] R-devel on FreeBSD: new C99 functions don't build

[Rainer Hurling]

On 18.05.2012 16:15 (UTC+1), Prof Brian Ripley wrote:
> On 15/05/2012 20:45, Rainer Hurling wrote:
>> On 15.05.2012 20:49 (UTC+1), Murray Stokely wrote:
>>> On Tue, May 15, 2012 at 10:05 AM, Rainer Hurling<rhurlin at gwdg.de> wrote:
>>>> About April 25th, there had been some changes within R-devel's
>>>> src/nmath/pnbeta.c (and probably some other relevant places) and now
>>>> building R-devel on FreeBSD 10.0-CURRENT (amd64) with gcc-4.6.4 and
>>>> math/R-devel (selfmade forked port from math/R) fails like this:
>>>
>>>> It seems, that at least one new C99 function (log1pl) is introduced in
>>>> R-devel, see
>>>>
>>>> src/nmath/pnbeta.c:l95
>>>> return (double) (log_p ? log1pl(-ans) : (1 - ans));
>>>
>>> AFAIK, Bruce Evans is not happy with the numerical accuracy of other
>>> open-source implementations of log1pl and so has blocked their
>>> inclusion in FreeBSD pending work on a better implementation.
>>>
>>> Can you put a conditional FreeBSD check here and use log1p instead of
>>> log1pl instead as a workaround?
>>>
>>> I can admire the insistence on correctness from the FreeBSD libm
>>> maintainers for their technical purity, but it can be a bit of a pain
>>> for things like this.
>>>
>>> - Murray
>>
>> I read about this discussion and in principle I concur with your
>> opinion. As a scientist I tend to expect greatest possible correctness
>> from a statistical routine, especially when it uses long double format.
>>
>> As a quick and dirty workaround I applied the following patch:
>>
>>
>> --- src/nmath/pnbeta.c.orig 2012-04-25 17:55:14.000000000 +0200
>> +++ src/nmath/pnbeta.c 2012-05-15 20:58:26.000000000 +0200
>> @@ -92,7 +92,11 @@
>> else {
>> if(ans > 1 - 1e-10) ML_ERROR(ME_PRECISION, "pnbeta");
>> if (ans > 1.0) ans = 1.0; /* Precaution */
>> +#if !defined(__FreeBSD__)
>> return (double) (log_p ? log1pl(-ans) : (1 - ans));
>> +#else
>> + return (double) (log_p ? log1p(-ans) : (1 - ans));
>> +#endif /* FreeBSD */
>> }
>> }
>>
>>
>> It builds and installs fine now and I hope there are no side effects ...
>
> Note though that R has *required* C99 compliance for quite a while, and
> that is not now even the current C standard. Using an OS that fails to
> comply to a 12-year-old standard is your own choice ... and you get the
> choice of using an equally old version of R.

Of course you are right with C99 compliance on FreeBSD. It is a long 
outstanding issue to get these long double functions in.

For me personally there are *many* reasons to use FreeBSD and at the 
moment R is one of only very few software packages we have serious 
trouble with C99 functions.

As you know, using an old version of R is not a real options. Because of 
that, we are looking at R-devel to find problems with FreeBSD in good time.

> I've added log1pl to the depressing list of FreeBSD workarounds:
> untested as I currently don't have access to a FreeBSD setup.

Many thanks for the patch. I built it and it is much more elegant than 
my workaround (HAVE_LOG1PL, log1p with double). And yes, the list is 
depressing.

> However, I think this has to come to an end: if a project such as
> Mingw-w64 can make the effort to supply a great deal of the C99
> functions missing from their OS then we must expect FreeBSD to do likewise.

As I said before, I agree with this point of view. But I am not a 
developer and a am not standing for the FreeBSD project. I am only an 
interested user and a maintainer for a few small FreeBSD ports 
(adaptions of third party software).

I will ask the FreeBSD people again for better C99 compliance ...

I really appreciate your help on this annoying issues and hope we will 
find a solution on FreeBSD in the near future.

Regards,
Rainer Hurling