#3214: [with patch, with positive review apart from one point] gcd needs
improved
coercion
------------------------------+---------------------------------------------
Reporter: novoselt | Owner: somebody
Type: defect | Status: reopened
Priority: blocker | Milestone: sage-3.3
Component: basic arithmetic | Resolution:
Keywords: |
------------------------------+---------------------------------------------
Changes (by cremona):
* summary: [with patch, needs review] gcd needs improved coercion =>
[with patch, with positive review apart from
one point] gcd needs improved coercion
Comment:
I applied the patch successfully to 3.2.3. Alex has done a good job of
testing -- I did not do a testall, just tested all in sage/rings.
It took me a few seconds (well, minutes) to see that gcd(nums)/lcm(denoms)
was the right answer. nice!
I found it hard to use the content function though. None of these work if
L is a list of integers or rationals: L.content(), content(L),
QQ.content(L), ZZ.content(L). Can we not have these? Also if v is an
element of {{{ZZ^n}}} then v.content() would also be useful. I could
perhaps be persuaded to put these enhancements into a different ticket.
I don't know what to do about the ginac failure:
{{{
sage: var('x,y',ns=1)
(x, y)
sage: f = -289*x*y - 17*x^2*y + 3/7*x^5*y + x^7 + 17*x^6 + 2/3*x^2 -
51/7*y^2 + 34/3*x + 2/7*y
sage: g = -289*x*y + 3/7*x^5*y - 17*x^13*y + x^18 + 2/3*x^13 + 17*x^6 -
51/7*y^2 + 34/3*x + 2/7*y
sage: f.gcd(g)
<boom>
}}}
It fails trying to convert a non-integral rational to an integer. Simpler
polys in place of f anf g work fine. As I don't even know what ginac is
or does I'm stuck!
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/3214#comment:13>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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