Re: [musl] catan(z)

[Damian McGuckin <damianm@esi.com.au>]

On Wed, 14 Aug 2024, Rich Felker wrote:

> If I'm following, it sounds like the current behavior is either a
> no-op or wrong and removing the _redupi step entirely would make it
> correct or at least closer to correct. Do you agree?

Just a no-op.  Unless there is some subtle reason why Moshier did this why 
I am too dumb to understand.  I think the issue was that back in the 80s 
when he wrote it, there were some unstandardised atan2() routines which 
(Moshier alluded to in his book and which) returned results in [0,2*pi] 
rather than the now standardized routines with return in [-pi,+pi] and he 
was handling those issues.

> Any suggestions for a test to run? I did some basic smoke testing for
> large positive real inputs and got expected results.

Not off hand. Other issues taking my brain cycles right nnow. Young Mr 
Nagy might have a better idea.

Thanks - Damian