On Thu, Sep 11, 2008 at 9:16 PM, Rob Beezer <[EMAIL PROTECTED]> wrote:
>
> I'm trying to compute the "product" of a couple of subgroups (the aim
> being to build a set that is not a subgroup). My students know the
> symmetries of a tetrahedron. Following code results in errors. I can
> change the final line to variations that are not useful (like just
> printing g and h individually) and the errors go away. Any
> thoughts on how to make this work?
This is a bug that we are tracking here:
http://trac.sagemath.org/sage_trac/ticket/4105
Here is a workaround:
tetra=AlternatingGroup(4)
stab1=PermutationGroup_subgroup(tetra, ["(1,2,3)"])
stab4=PermutationGroup_subgroup(tetra, ["(2,3,4)"])
for g in stab1:
for h in stab4:
print tetra(g)*tetra(h)
()
(2,3,4)
(2,4,3)
(1,2,3)
(1,3)(2,4)
(1,4,3)
(1,3,2)
(1,4,2)
(1,2)(3,4)
> Thanks,
> Rob
>
> Code:
>
> tetra=AlternatingGroup(4)
> stab1=PermutationGroup_subgroup(tetra, ["(1,2,3)"])
> stab4=PermutationGroup_subgroup(tetra, ["(2,3,4)"])
> for g in stab1:
> for h in stab4:
> print g*h
>
> Errors:
>
> Traceback (most recent call last): print (g*h)
> File "/opt/sage-3.0/local/lib/python2.5/site-packages/sympy/
> plotting/", line 3, in <module>
>
> File "element.pyx", line 1082, in
> sage.structure.element.MonoidElement.__mul__ (sage/structure/element.c:
> 7301)
> File "coerce.pyx", line 286, in
> sage.structure.coerce.CoercionModel_cache_maps.bin_op_c (sage/
> structure/coerce.c:5177)
> File "permgroup_element.pyx", line 463, in
> sage.groups.perm_gps.permgroup_element.PermutationGroupElement._r_action
> (sage/groups/perm_gps/permgroup_element.c:3239)
> File "permgroup_element.pyx", line 254, in
> sage.groups.perm_gps.permgroup_element.PermutationGroupElement.__init__
> (sage/groups/perm_gps/permgroup_element.c:1726)
> File "/opt/sage-3.0/local/lib/python2.5/site-packages/sage/groups/
> perm_gps/permgroup_named.py", line 130, in __init__
> raise ValueError, "n (=%s) must be >= 1"%n
> ValueError: n (=0) must be >= 1
>
> >
>
--
William Stein
Associate Professor of Mathematics
University of Washington
http://wstein.org
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