[SnapPea-planning] Finishing SnapPea 3.0

[Nathan Dunfield]

> On Thu, Nov 06, 2008 at 12:22:21PM -0500, Bill Thurston wrote:
>> 	b. The dirichlet domain command should be more robust,  either by
>> higher accuracy arithmetic or a smarter algorithm that
>> isn't killed by (I assume) floating point inaccuracy.
>
> Integration with Snap would do this, although a smarter algorithm
> would be faster.

Actually, I'm not sure this is true.  As I understand things, Snap  
does not actually include a version of the SnapPea kernel that works  
in high precision.   Rather, it uses the stock SnapPea kernel, but  
then takes the solutions to the gluing equations that the kernel finds  
and further "polishes" them in a separate stand-alone add-on which  
uses the PARI arbitrary-precision type.   Then it further uses the  
PARI library to identify the fields involved, etc.

To connect this to the funding issue, at some point Walter Neumann got  
a grant to rewrite Snap.  The idea, if I recall correctly, was to move  
it from C++ wrapped PARI over to the interpreted PARI language in  
order to make things more flexible/maintainable.   This did not  
actually happen as Oliver Goodman, who was going to do the work, left  
math at that point.  However, it does indicate that some funding for  
this type of project is available, though you'd have to ask Walter to  
find out where he got the grant from.  (Actually, the interpreted PARI  
language (GP) is rather dreadfully primitive, and these days one would  
want to use Sage (www.sagemath.org) instead.  Indeed as a proof of  
concept, I wrote a couple of pages of code which used Sage, rather  
than PARI, to replicate the very basic functions of Snap.)

I think Morwen Thistlethwaite was working on an extended precision  
SnapPea kernel at some point, but I don't know if anything came of it.

	Best,

	Nathan


-------------- next part --------------
A non-text attachment was scrubbed...
Name: snap.py
Type: text/x-python-script
Size: 3795 bytes
Desc: not available
Url : http://lists.bostoncoop.net/pipermail/snappea-planning/attachments/20081106/79ed43d0/attachment-0001.bin