#12149: float('nan')>1 crashes Sage.
--------------------------------+-------------------------------------------
Reporter: was | Owner: AlexGhitza
Type: defect | Status: needs_review
Priority: critical | Milestone: sage-4.8
Component: basic arithmetic | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author: William Stein
Merged: | Dependencies:
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Comment(by SimonKing):
Here are better timings (I hope):
Unpatched 4.8.alpha3:
{{{
sage: a = 1
sage: b = float(1)
sage: c = float(2.5)
sage: timeit("a==b",number=10^5)
100000 loops, best of 3: 320 ns per loop
sage: timeit("a==c",number=10^5)
100000 loops, best of 3: 323 ns per loop
}}}
With William's patch:
{{{
sage: a = 1
sage: b = float(1)
sage: c = float(2.5)
sage: d = float('nan')
sage: timeit("a==b",number=10^5)
100000 loops, best of 3: 336 ns per loop
sage: timeit("a==c",number=10^5)
100000 loops, best of 3: 333 ns per loop
sage: timeit("a==d",number=10^5)
100000 loops, best of 3: 281 ns per loop
}}}
With the sig_on/off alternative:
{{{
sage: a = 1
sage: b = float(1)
sage: c = float(2.5)
sage: d = float('nan')
sage: timeit("a==b",number=10^5)
100000 loops, best of 3: 369 ns per loop
sage: timeit("a==c",number=10^5)
100000 loops, best of 3: 369 ns per loop
sage: timeit("a==c",number=10^5)
100000 loops, best of 3: 369 ns per loop
sage: timeit("a==d",number=10^5)
100000 loops, best of 3: 3.92 µs per loop
}}}
I don't know the standard deviation of these timings (does "timeit" offer
such statistics?) - when repeating the tests, I sometimes got 380 ns, not
369 ns.
But the timings seem to suggest that William's patch is 10% faster in the
"number" case and is a lot faster in the "not a number" case.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12149#comment:16>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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