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Date: Sat, 28 Jul 2012 21:40:04 -0500
From: Stephen Montgomery-Smith <stephen@missouri.edu>
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To: Bruce Evans <brde@optusnet.com.au>
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Cc: freebsd-bugs@FreeBSD.org, Stephen Montgomery-Smith <stephen@FreeBSD.org>
Subject: Re: bin/170206: complex arcsinh, log, etc.
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On 07/28/2012 09:31 PM, Bruce Evans wrote:
> On Sat, 28 Jul 2012, Stephen Montgomery-Smith wrote:
>
>> OK.  This clog really seems to work.
>>
>> x*x + y*y - 1 is computed with a ULP less than 0.8.  The rest of the
>> errors seem to be due to the implementation of log1p.  The ULP of the
>> final answer seems to be never bigger than a little over 2.
>
> I really don't like this version.  If we want bignums and slowness, we
> can use lib[g]mp or even exec a mostly-interactive calculator (bc for
> portability, closed-source bigware for unportability).
>
> This version would have been useful in development to verify that the
> doubled or tripled floating point was as exact as intended.  Now writing
> it in your favourite interactive calculator is easiest, except for the
> problem of comparing the results.

I can understand your reticence.  I'll let you work some more on clog, 
and I will concentrate on the catrig stuff.

But did you see that I messed up my earlier error analysis of log1p(1+x)?

Also, if I had a log1pl, I would have used that.