Re: Proposal: Trigonometric functions in degrees

On Mon, Nov 30, 2015 at 11:11 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Michael Paquier <michael(dot)paquier(at)gmail(dot)com> writes:
>> On Mon, Nov 30, 2015 at 10:36 PM, Michael Paquier wrote:
>>> Instinctively, it seems to me that we had better return Nan for the
>>> new asind and acosd when being out of range for OSX, Linux will
>>> complain about an out-of-range error so the code is right in this
>>> case.
>
>> This is still mentioned upthread btw. And it does not seem to be a
>> good idea to change this platform dependent behavior by throwing an
>> error on the old functions, neither does it seem user-friendly to have
>> inconsistent results for the XXX function and its XXXd equivalent.
>
> FWIW, I think that probably the best course of action is to go ahead
> and install POSIX-compliant error checking in the existing functions
> too. POSIX:2008 is quite clear about this:
>
> : An application wishing to check for error situations should set errno to
> : zero and call feclearexcept(FE_ALL_EXCEPT) before calling these
> : functions. On return, if errno is non-zero or fetestexcept(FE_INVALID |
> : FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
> : occurred.

OK, I have to admit I didn't know this part.

> Although I'm not too sure about Windows, the inconsistent results
> we're getting on OS X are certainly from failure to adhere to the spec.

Windows complains about out-of-range errors contrary to OSX on for
example asin or acos. So for once Linux and Windows agree with each
other.

> I concur with Peter's opinion that this is material for a separate
> patch, but it seems like it's one that had better go in first.

(I think you mean Dean here and not Peter).
--
Michael