#2329: add interface to Pari's rnfisnorm
-----------------------------------------+----------------------------------
Reporter: craigcitro | Owner: craigcitro
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-4.6.1
Component: number fields | Keywords: editor_craigcitro
Author: Craig Citro, Marco Streng | Upstream: N/A
Reviewer: Nick Alexander | Merged:
Work_issues: bug in Pari 2.3.5 |
-----------------------------------------+----------------------------------
Changes (by fwclarke):
* work_issues: compilation problems => bug in Pari 2.3.5
Comment:
Replying to [comment:15 davidloeffler]:
> ..., it *still* doesn't work:
{{{
sage -t number_field_element.pyx
**********************************************************************
File "/storage/masiao/sage-4.6.alpha1/devel/sage-
hacking/sage/rings/number_field/number_field_element.pyx", line 971:
sage: (beta/2).is_norm(L)
Exception raised:
Traceback (most recent call last):
...
File "gen.pyx", line 9470, in sage.libs.pari.gen._pari_trap
(sage/libs/pari/gen.c:45353)
PariError: (5)
**********************************************************************
}}}
> At that point I gave up. Sorry. That's "needs work".
Looks like a Pari bug. This is what the doctest asks Pari to do (with the
equivalent of beta.is_norm(L) first):
{{{
trousseau-bash% sage-4.6/sage -gp
GP/PARI CALCULATOR Version 2.4.3 (development
svn-12577:12605)
i386 running darwin (x86-64/GMP-4.2.1 kernel) 64-bit
version
...
parisize = 8000000, primelimit = 500509
? bnf = bnfinit(y^3 + 5);
? p = x^2 + x + Mod(y, y^3 + 5);
? T = rnfisnorminit(bnf, p);
? rnfisnorm(T, Mod(y, y^3 + 5))
%4 = [Mod(x, x^2 + x + Mod(y, y^3 + 5)), 1]
? rnfisnorm(T, Mod(y/2, y^3 + 5))
*** at top-level: rnfisnorm(T,Mod(y/2,
*** ^--------------------
*** rnfisnorm: zero argument in factorint.
*** Break loop: type 'break' to go back to GP
break> break
}}}
But previously, it worked alright:
{{{
trousseau-bash% sage-4.5.3/sage -gp
GP/PARI CALCULATOR Version 2.3.5 (released)
i386 running darwin (x86-64/GMP-4.2.1 kernel) 64-bit
version
...
parisize = 8000000, primelimit = 500000
? bnf = bnfinit(y^3 + 5);
? p = x^2 + x + Mod(y, y^3 + 5);
? T = rnfisnorminit(bnf, p);
? rnfisnorm(T, Mod(y, y^3 + 5))
%4 = [Mod(-x, x^2 + x + Mod(y, y^3 + 5)), 1]
? rnfisnorm(T, Mod(y/2, y^3 + 5))
%5 = [Mod(Mod(-1/2, y^3 + 5)*x, x^2 + x + Mod(y, y^3 + 5)), 2]
?
}}}
Note also that the two versions give a different result at %4.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/2329#comment:17>
Sage <http://www.sagemath.org>
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