#12186: Faster norm calculations
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Reporter: MvanBeek | Owner: tbd
Type: PLEASE CHANGE | Status: new
Priority: minor | Milestone: sage-4.8
Component: PLEASE CHANGE | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Using a relative norm calculation is far slower than using an absolute
norm calculation. The first should therefore be avoided if possible. What
is needed is a patch that avoids using relative norm calculations when
they are not necessary. The problem is well summarized in the following
example:
{{{
sage: K1.<a1> = CyclotomicField(11)
sage: K2.<a2> = K1.extension(x!^2 - 3)
sage: K3.<a3> = K2.extension(x!^2 + 1)
sage: t=a1+6*a2+a3*a1
sage: %time t.norm()
CPU times: user 0.10 s, sys: 0.00 s, total: 0.10 s
Wall time: 0.11 s
46593592840125350650995659797233874763776
sage: %time t.norm(QQ)
CPU times: user 2.11 s, sys: 0.01 s, total: 2.12 s
Wall time: 2.23 s
46593592840125350650995659797233874763776
}}}
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12186>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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