#12923: Comparison of vectors is O(n) even in the simple cases
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Reporter: hivert | Owner: jason, was
Type: defect | Status: needs_work
Priority: major | Milestone: sage-5.1
Component: linear algebra | Resolution:
Keywords: vector equality days38 | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Florent Hivert | Merged in:
Dependencies: | Stopgaps:
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Changes (by tscrim):
* status: needs_review => needs_work
Comment:
It works fine for integers, but observe the following:
{{{
sage: l = 1000; v1 = vector(ZZ, [0]*l); v2 = vector(QQ, [1]*l)
sage: %timeit v1 == v2
5 loops, best of 3: 2.25 ms per loop
sage: %timeit v1 == v2
125 loops, best of 3: 3.24 ms per loop
sage: %timeit v1 == v2
125 loops, best of 3: 3.27 ms per loop
sage: %timeit v1 == v2
125 loops, best of 3: 3.35 ms per loop
sage: l = 2000; v1 = vector(ZZ, [0]*l); v2 = vector(QQ, [1]*l)
sage: %timeit v1 == v2
5 loops, best of 3: 4.72 ms per loop
sage: %timeit v1 == v2
125 loops, best of 3: 6.81 ms per loop
sage: %timeit v1 == v2
125 loops, best of 3: 6.64 ms per loop
}}}
I can't test any higher because running these tests completely kills my
memory (the first comparison will allocate ~150MB RAM, the second ~450MB
RAM). It only allocates when I call the comparison. Also my memory usage
did not drop when I reassign v1 and v2.
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12923#comment:3>
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