#4000: Implement QQ['x'] via Flint ZZ['x'] + denominator
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Reporter: malb | Owner: somebody
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-4.3.2
Component: basic arithmetic | Keywords:
Author: Sebastian Pancratz, Martin Albrecht | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by spancratz):
Here is a simpler instance of the problem:
{{{
sage: R.<x> = QQ[]
sage: f = 3/2*x - 1/3
sage: %time _ = f % f
CPU times: user 5.67 s, sys: 0.17 s, total: 5.84 s
Wall time: 5.86 s
}}}
I do *not* think that the problem is a coercion problem. After inserting
"print" statements into the Cython code at various points, I instead think
the code in the block from line 881 in fmpq_poly_linkage.pxi actually
takes this long, although I do not understand at all why this might be the
case.
The two lines at actually seem to take time (assuming that inserting
"print" statements is a valid way to determine this) are
{{{
fmpz_pow_ui(t, lead, m)
fmpz_mul(r.den, t, a.den)
}}}
but, once again, I've got not clue why this might be the case.
Tomorrow or on Tuesday, I will try to reproduce the problem in plain C.
If I manage to do this, I'll forward it to Bill Hart. If not, I wouldn't
really know what else to look into.
Sebastian
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4000#comment:44>
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