#15820: Implement sequences of bounded integers
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Reporter: SimonKing | Owner:
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-6.3
Component: algebra | Resolution:
Keywords: sequence bounded | Merged in:
integer | Reviewers:
Authors: Simon King | Work issues: Fix flakyness in
Report Upstream: N/A | adding sequences
Branch: | Commit:
u/SimonKing/ticket/15820 | 735939e593c9c302ff42c4973cbfe2e48eb22644
Dependencies: | Stopgaps:
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Comment (by SimonKing):
Current status is a struggle with sub-sequence recognition in the presence
of trailing zeroes.
Here is the type of examples that I propose:
- Use a sequence of length 7 with a bound of 32. Then, we need 35 bit to
store the sequence.
- At least on my machine, a GMP limb comprises 32 bit. Hence, the above
sequence fits into two limbs, we only use three bit of the second limb.
- Choose the last item of the sequence such that it fits into 2 bit. Then,
the three bit stored in the second limb are zero.
- Now, do an operation that involves a `mpz_*` function to create a new
bounded integer sequence, ''only'' adding trailing zeroes. This currently
is in concatenation and slicing. This may result in GMP cutting off the
trailing zeroes.
When we then do operations involving `mpn_*` functions, it is needed to
take care of the cut off bits (and treat them as zero). My current private
branch (not pushed yet) involves several tests that are failing with the
branch currently attached here, but succeed in my current branch.
Still failing is this:
{{{
sage: X = BoundedIntegerSequence(21, [4,1,6,2,7,2,3])
sage: S = BoundedIntegerSequence(21, [0,0,0,0,0,0,0])
sage: loads(dumps(X+S))
<4, 1, 6, 2, 7, 2, 3, 0, 0, 0, 0, 0, 0, 0>
sage: loads(dumps(X+S)) == X+S
True
sage: T = BoundedIntegerSequence(21,
[0,4,0,1,0,6,0,2,0,7,0,2,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0])
sage: T[3::2]==(X+S)[1:]
True
sage: T[3::2] in X+S
False # should return True!
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/15820#comment:80>
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