Re: Proposal: Trigonometric functions in degrees

Michael Paquier <michael.paquier@gmail.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.

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.

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.
        regards, tom lane