#14007: When computing determinant over GF(p), don't lift to ZZ
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Reporter: jdemeyer | Owner: jason, was
Type: enhancement | Status: needs_work
Priority: blocker | Milestone: sage-5.7
Component: linear algebra | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers: Charles Bouillaguet
Authors: Jeroen Demeyer | Merged in:
Dependencies: | Stopgaps:
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Comment (by Bouillaguet):
The threshold is very clearly at ``2^64``. This is with the patch:
{{{
sage: p = next_prime(2^64-60)
sage: M = random_matrix( Integers(p), 75*5 )
sage: M2 = matrix(ZZ, M)
sage: time d = M.det()
Time: CPU 3.49 s, Wall: 3.49 s # PARI prime case is faster
sage: time d = M2.det()
Time: CPU 6.29 s, Wall: 5.09 s
sage: p = next_prime(2^64)
sage: M = random_matrix( Integers(p), 75*5 )
sage: M2 = matrix(ZZ, M)
sage: time d = M.det()
Time: CPU 8.83 s, Wall: 8.83 s # PARI prime case is slower
sage: time d = M2.det()
Time: CPU 6.77 s, Wall: 5.52 s
}}}
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14007#comment:7>
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