Low Dimensional Topology

February 23, 2010

SnapPy 1.1 released

Marc Culler and I have released version 1.1 of SnapPy.   Recently added features include:

  • Better Chern-Simons. The original SnapPea kernel could only compute the CS invariant some of the time.   Matthias Goerner has contributed an implementation of Zickert’s algorithm which works in many more cases. This is the first major code addition by someone other than Marc or I, so many thank to Matthias for making this available!
  • Now with even more manifolds. Due to the kindness of Morwen Thistlethwaite, SnapPy now comes with almost 200,000 more manifolds: a census of links through 14 crossings (MorwenLinks) and all orientable cusped manifolds with 8 tetrahedra (denoted e.g. “t01234” and part of OrientableCuspedCensus).
  • General Improvements: Improved UI features relating to saving and loading links, better Windows 7 support, various bug fixes.

There’s an example of all the new features after the jump. Enjoy!

In [1]: M = Manifold("t01234")

In [2]: M.num_tetrahedra()
Out[2]: 8

In [3]: M.chern_simons()
Out[3]: 0.041534768860165182

In [4]: M.chern_simons(old_algorithm=True)
ValueError: Chern-Simons invariant isn't currently known

In [5]: C = MorwenLinks(2) # All those with 2 components

In [5]: len(C) # The bulk of the added manifolds!
Out[5]: 77329

In [6]: M = C[-1] # The last one in the list, a 14 crossing example

In [7]: M
Out[7]: DT[nbgghjMiknldacgeBf](0,0)(0,0)

In [7]: M.volume(complex_volume=True)
Out[7]: (23.288433533395747+3.8411820987874687j)


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