#10153: Canonical generator matrices for linear codes and their automorphism 
groups
------------------------------+---------------------------------------------
   Reporter:  tfeulner        |       Owner:  wdj                               
         
       Type:  enhancement     |      Status:  needs_work                        
         
   Priority:  major           |   Milestone:  sage-4.7                          
         
  Component:  coding theory   |    Keywords:  Automorpism group, canonical 
representative
     Author:  Thomas Feulner  |    Upstream:  N/A                               
         
   Reviewer:                  |      Merged:                                    
         
Work_issues:                  |  
------------------------------+---------------------------------------------

Comment(by wdj):

 Installed fine on a 10.6.6 mac running 4.7.a1. However, there was the
 following doctest failure:

 {{{
 sage -t -force_lib "devel/sage/sage/coding/code_can.pyx"
 **********************************************************************
 File
 "/Volumes/Bay2/sagefiles2/sage-4.7.alpha1/devel/sage/sage/coding/code_can.pyx",
 line 495:
     sage: canonizer._latex_()
 Expected:
     '\\textnormal{Canonization object for linear codes over finite fields
 or } `\\ZZ_4`\\textnormal{. The actual code is generated
 by}\\\\\\left(\\begin{array}{rrrrrrr}\n1 & 0 & 0 & 1 & 0 & 1 & 0 \\\\\n0 &
 1 & 0 & 1 & 0 & 1 & 1 \\\\\n0 & 0 & 1 & 1 & 0 & 0 & 1 \\\\\n0 & 0 & 0 & 0
 & 1 & 1 & 1\n\\end{array}\\right)'
 Got:
     '\\textnormal{Canonization object for linear codes over finite fields
 or } `\\ZZ_4`\\textnormal{. The actual code is generated
 by}\\\\\\left(\\begin{array}{rrrrrrr}\n1 & 0 & 0 & 0 & 0 & 1 & 1 \\\\\n0 &
 1 & 0 & 0 & 1 & 0 & 1 \\\\\n0 & 0 & 1 & 0 & 1 & 1 & 0 \\\\\n0 & 0 & 0 & 1
 & 1 & 1 & 1\n\\end{array}\\right)'
 **********************************************************************
 File
 "/Volumes/Bay2/sagefiles2/sage-4.7.alpha1/devel/sage/sage/coding/code_can.pyx",
 line 358:
     sage: [a[0] * Gamma.apply_morphism(a[2]) * a[1] == Gamma for a in
 gens]
 Expected:
     [True, True, True, True, True, True, True, True, True, True, True,
 True, True, True, True]
 Got:
     [True, True, True, True, True, True, True, True, True, True, True,
 True, True, True]
 **********************************************************************
 File
 "/Volumes/Bay2/sagefiles2/sage-4.7.alpha1/devel/sage/sage/coding/code_can.pyx",
 line 476:
     sage: repr(canonizer)
 Expected:
     'Canonization object for linear codes over finite fields or `\\ZZ_4`.
 The actual code is generated by\n[1 0 0 1 0 1 0]\n[0 1 0 1 0 1 1]\n[0 0 1
 1 0 0 1]\n[0 0 0 0 1 1 1]'
 Got:
     'Canonization object for linear codes over finite fields or `\\ZZ_4`.
 The actual code is generated by\n[1 0 0 0 0 1 1]\n[0 1 0 0 1 0 1]\n[0 0 1
 0 1 1 0]\n[0 0 0 1 1 1 1]'
 **********************************************************************
 3 items had failures:
    1 of   7 in __main__.example_10
    1 of  44 in __main__.example_6
    1 of   7 in __main__.example_9
 ***Test Failed*** 3 failures.
 For whitespace errors, see the file
 /Users/davidjoyner/.sage//tmp/.doctest_code_can.py
          [43.1 s]

 ----------------------------------------------------------------------
 The following tests failed:


         sage -t -force_lib "devel/sage/sage/coding/code_can.pyx"
 Total time for all tests: 43.2 seconds
 }}}

 Honestly, I'm not sure the best way of returning the component of the
 automorphism group which corresponds to field automorohisms. Sage does not
 seem to have the Galois action on a vector space such as GF(4,"a")^3
 implemented. You can try to return an element of this component as a tuple
 of integers which give the exponents of a Frobenius action. You might also
 just return it as a separate abelian group. There are probably other ideas
 out there too. How does Magma do it?

-- 
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10153#comment:6>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica, 
and MATLAB

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