Judging from the error message "unable to coerce from a finite field other than the prime subfield", it seems that in Martin's examples a coercion is attempted from GF(p^a) to GF(p^b) where a>1. In David's example, the larger field is GF(3^2) so any coercion would be coming from GF(3), hence not covered by the error message.
So I don't think it has to do with trac #5491. It is either a problem with Sage finite fields, or with translating between Gap finite fields and Sage finite fields. I'll have a closer look later today and open a ticket. Best, Alex On Mon, Mar 16, 2009 at 8:19 AM, David Joyner <wdjoy...@gmail.com> wrote: > > This doesn't seem to happen for smaller values, > > sage: n = 2; q = 3 > sage: H = PSL(n,q^2) > sage: H.center() > Permutation Group with generators [()] > sage: n = 2; q = 2 > sage: H = PSL(n,q^2) > sage: H.center() > Permutation Group with generators [()] > > so maybe the problem is related to > http://trac.sagemath.org/sage_trac/ticket/5491? > > > > On Sun, Mar 15, 2009 at 3:07 PM, Martin Mereb <mme...@gmail.com> wrote: > > > > and > > also got this problem > > > > n=3;q=4; > > > > H = SL(n,q^2); > > H.center() > > > > Traceback (most recent call last): > > File "<stdin>", line 1, in <module> > > File "/home/sage/sagenb/sage_notebook/worksheets/Tincho/3/code/3.py", > > line 10, in <module> > > H.center() > > File > "/home/sage/sage_install/sage-a/local/lib/python2.5/site-packages/SQLAlchemy-0.4.6-py2.5.egg/", > > line 1, in <module> > > > > File > "/home/sage/sage_install/sage-a/local/lib/python2.5/site-packages/sage/groups/matrix_gps/matrix_group.py", > > line 678, in center > > self.__center = MatrixGroup([g._matrix_(F) for g in G]) > > File > "/home/sage/sage_install/sage-a/local/lib/python2.5/site-packages/sage/interfaces/gap.py", > > line 1131, in _matrix_ > > entries = [[R(self[r,c]) for c in range(1,m+1)] for r in range(1,n+1)] > > File "finite_field_givaro.pyx", line 586, in > > sage.rings.finite_field_givaro.FiniteField_givaro.__call__ > > (sage/rings/finite_field_givaro.cpp:4680) > > File > "/home/sage/sage_install/sage-a/local/lib/python2.5/site-packages/sage/interfaces/gap.py", > > line 1248, in gfq_gap_to_sage > > return F(K(g**e)) > > File "finite_field_givaro.pyx", line 530, in > > sage.rings.finite_field_givaro.FiniteField_givaro.__call__ > > (sage/rings/finite_field_givaro.cpp:4005) > > TypeError: unable to coerce from a finite field other than the prime > subfield > > > > > > > > > > > -- Alex Ghitza -- Lecturer in Mathematics -- The University of Melbourne -- Australia -- http://www.ms.unimelb.edu.au/~aghitza/ --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
