Subject: Generalized Lambert W function - premature commit
From: Richard Fateman
Date: Thu, 24 May 2012 06:30:02 -0700
On 5/24/2012 3:20 AM, David Billinghurst wrote:
>
>
> I have just checked in a generic version using the bigfloat package.
> Much neater. I removed the guard digits from the bfloat calcs - it
> was a nasty hack that didn't always work - so the results may change
> slightly. I will just make a note in the manual that the final digits
> may be wrong, and to suggest users check using higher precision if it
> matters.
I hope you are talking about just the final digits of the bfloat of
Lambert W, not the final digits of bfloats.
The cost of getting the rounding correct on bfloat add/subtract is
substantial, but (when I wrote it) deemed essential
because IEEE standard was doing the right thing. I hope that has not
been removed! (Actually, I wrote a slimmer
faster non-round-to-nearest version also. That may be hanging around in
the code somewhere...)
RJF