#13951: (non)archimedian_local_height broken for rational points on elliptic 
curves
over Q
---------------------------------------------+------------------------------
       Reporter:  pbruin                     |         Owner:  cremona          
        
           Type:  defect                     |        Status:  needs_review     
        
       Priority:  major                      |     Milestone:  sage-5.11        
        
      Component:  elliptic curves            |    Resolution:                   
        
       Keywords:  local heights              |   Work issues:                   
        
Report Upstream:  N/A                        |     Reviewers:  John Cremona, 
Peter Bruin
        Authors:  Peter Bruin, John Cremona  |     Merged in:                   
        
   Dependencies:  #12509, #13953, #14609     |      Stopgaps:                   
        
---------------------------------------------+------------------------------

Old description:

> Computing local heights uses functions that are only available when the
> base field is a NumberField, and not over the RationalField:
>
> {{{
> sage: E = EllipticCurve([0, 0, 0, -36, 0])
> sage: P = E(-3, 9)
> sage: P.archimedian_local_height()
> ...
> AttributeError: 'RationalField_with_category' object has no attribute
> 'places'
> sage: P.nonarchimedian_local_height()
> ...
> AttributeError: 'RationalField_with_category' object has no attribute
> 'factor'
> }}}
>
> Note: at the moment this bug only shows up for non-torsion points because
> of bug #13953 (asking for local heights of torsion points always returns
> 0, which is in general incorrect).
>
> Apply: trac13951-local_heights.patch, trac13951-local_heights_2.patch

New description:

 Computing local heights uses functions that are only available when the
 base field is a NumberField, and not over the RationalField:

 {{{
 sage: E = EllipticCurve([0, 0, 0, -36, 0])
 sage: P = E(-3, 9)
 sage: P.archimedian_local_height()
 ...
 AttributeError: 'RationalField_with_category' object has no attribute
 'places'
 sage: P.nonarchimedian_local_height()
 ...
 AttributeError: 'RationalField_with_category' object has no attribute
 'factor'
 }}}

 Note: at the moment this bug only shows up for non-torsion points because
 of bug #13953 (asking for local heights of torsion points always returns
 0, which is in general incorrect).

 Apply: [attachment:trac13951-local_heights.patch],
 [attachment:trac13951-local_heights_2.patch],
 [attachment:trac13951-docstring_raw.patch]

--

Comment (by pbruin):

 Patchbot complains about the non-ASCII character in "Néron".  I assume
 this isn't a problem, cf. the discussion about Ш in a docstring in #14561.
 The relevant file is already UTF-8-encoded; I'll just make the docstring
 start with `r"""`.

-- 
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13951#comment:31>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica, 
and MATLAB

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