#11891: NumberField(...).pari_polynomial() should return an integral polynomial
-----------------------------+----------------------------------------------
   Reporter:  jdemeyer       |          Owner:  davidloeffler 
       Type:  enhancement    |         Status:  needs_review  
   Priority:  major          |      Milestone:  sage-4.7.3    
  Component:  number fields  |       Keywords:                
Work_issues:                 |       Upstream:  N/A           
   Reviewer:                 |         Author:  Jeroen Demeyer
     Merged:                 |   Dependencies:                
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Comment(by was):

 The code looks good, and passes tests, and it means we can at least
 compute discriminants.

 The first and second things I try still don't work though, and I'm curious
 what you think about this:
 {{{
 sage: k.<a, c> = NumberField([x^2 + 1/3, x^2 + 1/4])
 sage: k
 Number Field in a with defining polynomial x^2 + 1/3 over its base field
 sage: a+c
   ***   Warning: non-monic polynomial. Result of the form [nf,c].
 ERROR: An unexpected error occurred while tokenizing input
 ...
 BOOM!
 sage: k.relative_discriminant()
   ***   Warning: non-monic polynomial. Result of the form [nf,c].
 BOOM!
 }}}


 Side Remarks: 1. I've always intended to just rewrite number fields to
 completely use
 {{{
 sage.schemes.elliptic_curves.heegner.make_monic
 }}}
 behind the scenes, and do *everything* that involves PARI in all cases
 using a monic integral polynomial, and only convert to the user's
 representation for input and output.  I wish I had done that when I was
 first writing number fields.


 2. This is disturbing:
 {{{
 sage: K.<I> = NumberField(x^2+1)
 sage: K.pari_polynomial()
 x^2 + 1
 sage: K.pari_polynomial('I')
 0
 }}}
 I would rather get an error message in the latter case.  What do you
 think?  If you agree, could you open a ticket?


 Anyway, I'll wait for your comments...

-- 
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11891#comment:3>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica, 
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