#5698: [with patch; needs review] Sage 3.4.1.rc1: doctest failure in
schemes/elliptic_curves/monsky_washnitzer.py
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Reporter: mabshoff | Owner: mabshoff
Type: defect | Status: new
Priority: blocker | Milestone: sage-3.4.1
Component: doctest | Keywords:
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Comment(by was):
This is a bug in FLINT:
{{{
sage: R.<t> = Zmod(next_prime(8000^3))[]
sage: f = R.random_element(degree=3200)
sage: pari(f)*pari(f) == pari(f*f)
False
}}}
This happens for most numbers > 8000 above, but not for smaller numbers.
If we downgrade to the previous FLINT, the problem goes away.
This is an "aliasing problem".
{{{
wst...@sage:/scratch/mabshoff/sage-3.4.1.rc1$ ./sage
----------------------------------------------------------------------
| Sage Version 3.4.1.rc1, Release Date: 2009-04-05 |
| Type notebook() for the GUI, and license() for information. |
----------------------------------------------------------------------
sage: R.<t> = Zmod(next_prime(8000^3))[]
sage: f = R.random_element(degree=3200)
sage: pari(f)*pari(f) == pari(f*f)
sage: sage: R.<t> = Zmod(next_prime(8000^3))[]
sage: sage: f = R.random_element(degree=3200)
sage: sage: pari(f)*pari(f) == pari(f*f)
False
sage:
sage: g = f+1
sage: pari(f)*pari(g) == pari(f*g)
True
sage: g = f+2
sage: pari(f)*pari(g) == pari(f*g)
True
sage: pari(f)*pari(g-2) == pari(f*(g-2))
True
sage: pari(f)*pari(f) == pari(f*f)
False
sage: pari(f)*pari(f+1-1) == pari(f*(f+1-1))
True
}}}
Turning off using David Harvey's znpoly fixes this problem. The spkg up
here turns off znpoly. With this the whole test suite passes fine:
http://sage.math.washington.edu/home/wstein/patches/flint-1.2.4.p1.spkg
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/5698#comment:1>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
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