Comment #23 on issue 3501 by [email protected]: Missing partitions in
sympy.utilities.iterables.multiset_partitions
http://code.google.com/p/sympy/issues/detail?id=3501
git checkout -b kbins smichr/kbins
That's what I would do...looks good.
You *might* consider adding something like the following to the
comments/doc:
I added the excellent comments (with very minor modification) to the notes
of `_set_partitions`.
The helper function _partition provides similar, but lighter-weight
functionality to that provided by the classmethod
combinatorics.partitions.**Partition.from_rgs(). Perhaps worth a
cross-reference?
I added it as a See Also
I also wrote a tester to sanity check. I am attaching it to this
post. Perhaps something like test_partitions() is worth incorporating
into the tests? The one-off tests at the bottom of this most
likely duplicate tests you already have.
-----------------
multiset_partitions
--> docstring
The analytical discussion under "Counting"
These formulas only apply in the set case. Multisets are more
complicated... perhaps:
done
If the input is a set (no repeated elements), the number of partitions
returned is given by the bell number ...
----------------
I looked briefly at the new multiset_combinations and
multiset_permutations and didn't see anything to argue with. (Except
of course the TODO comment in multiset_combinations).
The TODO is done, too, and now my brain is mush.
Misc - combinatorics.RGS_enum() seems to be computing the same thing
as bell()? Worth a cleanup or cross reference?
Other than the calculation for numbers < 1, it appears to be the same and
much faster, so I imported and used bell there:
RGS_enum(16)
10480142147
bell(16)
10480142147
from timeit import timeit
timeit('RGS_enum(23)','from sympy.combinatorics import *', number=100)
0.46608495712280273
timeit('RGS_enum(23)','from sympy import bell as RGS_enum', number=100)
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