#14704: Use GMP's mpz_t for bitsets
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Reporter: Stefan | Owner: jason
Type: enhancement | Status: new
Priority: minor | Milestone: sage-wishlist
Component: misc | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
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Comment (by leif):
Replying to [comment:9 robertwb]:
> The only way to know for sure is to code something up and compare
performance, until then all discussion is rather hypothetical (and I could
see things going both ways, but probably would place my bet on mpz_t.)
Well, you do not only need different implementations, but also typical use
cases to make comparisons meaningful.
[[BR]]
> Note that mpz_t could be a member of the bitset struct (if indeed
another struct is needed) which would avoid one level of indirection. It
may be worth looking at using the mpn structures directly for this low-
level behavior as well.
I actually did not think of not making it part of some bitset structure.
(But the pointer to the limbs remains.)
Note that GMP operates on limbs, so the (logical) "size" of a plain
`mpz_t` bitset would always be a multiple of `BITS_PER_LIMB`. (And we
certainly don't need the "sign" of a bitset; GMP's treatment may even
disturb.)
It would probably make sense to (optionally) keep track of the least and
largest element contained in a set, and perhaps its cardinality as well,
depending on the application.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14704#comment:10>
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