#4782: construction of some relative quadratic extensions is SERIOUSLY FRICKIN's
FOO-bar'd
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Reporter: was | Owner: was
Type: defect | Status: new
Priority: major | Milestone: sage-3.2.2
Component: number theory | Keywords:
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Try this carefully with your finger on kill -9:
{{{
sage: NumberField(x^2 + 79*x - 60, 'a').extension(x^2 - 69*x + 38,'b')
}}}
On sage.math top shows pretty quickly over 6.9GB memory usage!
{{{
15392 was 25 0 8219m 6.9g 21m R 100 10.9 0:53.76 sage-ipython
}}}
The discriminants aren't very big:
{{{
sage: R.<x> = QQ[]
sage: disc(x^2 + 79*x-60)
6481
sage: disc(x^2 - 69*x + 38)
4609
}}}
Same behavior with Proof false:
{{{
sage: proof.all(False)
sage: NumberField(x^2 + 79*x - 60, 'a').extension(x^2 - 69*x + 38,'b')
...hell....
}}}
Giving both polys at once (which maybe use polcompositum) works:
{{{
sage: NumberField([x^2 + 79*x-60, x^2 - 69*x + 38], 'a')
*** Warning: insufficient precision for fundamental units, not given.
Number Field in a0 with defining polynomial x^2 + 79*x - 60 over its base
field
}}}
Basically there is something very wrong with how we make relative
fields... probably because of something very very wrong in the core of
pari itself (and it's relative number fields).
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4782>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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