I'm glad that CHomP is going in and that there is work being done on it. Even though it doesn't need a vote, feel free to add me as a reviewer to any related tickets. I've meant to look in to adding it and other things related to dynamical systems for a long time and haven't had the time (e.g. PyDSTool, AUTO).
-Marshall On Feb 18, 5:56 pm, John H Palmieri <jhpalmier...@gmail.com> wrote: > CHomP is a free (GPL version 2) software package for computing > homology (CHomP stands for Computation Homology Project.) See > chomp.rutgers.edu for some more information. I've prepared an > experimental spkg for it: > > http://sage.math.washington.edu/home/palmieri/SPKG/chomp-20100213.spkg > > If you successfully install it, it will put programs "homchain", > "homcubes", and "homsimpl" in SAGE_LOCAL/bin; these compute homology > of, respectively, chain complexes, cubical complexes, and simplicial > complexes, and they're much faster than what's currently in Sage for > homology computations. I've gotten this to compile without difficulty > on an Intel Mac running OS X 10.6 as well as on sage.math. I haven't > tried any other platforms, mainly because I don't have easy access to > them. If people could try installing it, that would be great. > > It would be nice if it were included as an experimental spkg, for > download from the official Sage sites. I think we need to vote on > this. Opinions? > > If you've managed to compile it and you want to see it in action, you > have several choices: run "tar jxf" on the spkg and look in the > "examples" directory. Alternatively, you can download this patch for > the Sage library: > > http://sage.math.washington.edu/home/palmieri/misc/Cell_complexes.patch > > This implements lots of things, but one of them is an interface to > CHomP: if CHomP is present, Sage will automatically use it to compute > homology groups. CHomP can't handle rational coefficients, so you can > see difference in timings this way. On my iMac: > > sage: T = simplicial_complexes.Torus() > sage: X = T.product(T) > sage: time X.homology() # uses CHomP > CPU times: user 0.35 s, sys: 0.04 s, total: 0.39 s > Wall time: 0.92 s > {0: 0, 1: Z x Z x Z x Z, 2: Z^6, 3: Z x Z x Z x Z, 4: Z} > sage: X = T.product(T) > sage: time X.homology(base_ring=QQ) # doesn't use CHomP > CPU times: user 16.88 s, sys: 0.18 s, total: 17.06 s > Wall time: 17.66 s > ... > > (CHomP also can't compute cohomology, so that's another way of seeing > timing differences.) CHomP will also compute generators in homology, > whereas the Sage version doesn't do this: do > X.homology(generators=True). > > -- > John -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
