On Apr 29, 2010, at 9:54 AM, Pierre wrote:
Dear all,
Not sure if this is for sage-devel or sage-support. Here's a
'benchmark' which I find stunning:
sage: A= MatrixSpace(QQ['t'], 8).random_element()
sage: %time B= A*A
CPU times: user 0.04 s, sys: 0.00 s, total: 0.04 s
Wall time: 0.04 s
sage: C= MatrixSpace(QQ['t'].fraction_field(), 8).random_element()
sage: %time D= C*C
CPU times: user 17.28 s, sys: 0.19 s, total: 17.48 s
Wall time: 17.57 s
Is something wrong ? 17 seconds instead of 0.04 ? 400 times slower ?
is it my particular system ? is there an option perhaps for performing
the computations without simplifying the fractions, or something ?
(of course this came up in an example more interesting than squaring
random matrices...)
It is my humble opinion that this issue is serious. Rational fractions
tend to be all over the place in formal computations.
any thoughts ?
This is a known bug, and almost fixed:
http://trac.sagemath.org/sage_trac/ticket/4000
- Robert
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