awesome! perfect solution :-)
thanks !
On Wednesday, March 30, 2016 at 2:22:31 PM UTC+2, Volker Braun wrote:
>
> The "in" operator is the "\in" function in gap:
>
> sage: G = libgap.SymmetricGroup(3)
> sage: g = libgap.eval("(1,2,3)")
> sage: isContainedIn = libgap.function_factory(r'\in')
> sage: isContainedIn(g, G)
> true
>
>
>
> On Wednesday, March 30, 2016 at 11:39:14 AM UTC+2, Pierre wrote:
>>
>> Hi !
>>
>> I've been playing with libgap, which is great (I love the fact that lists
>> returned by GAP now start at 0...)
>>
>> I have been unable, however, to elegantly work around the following
>> simple taks. Suppose:
>>
>> sage: G= libgap.SymmetricGroup(3)
>> sage: g= libgap.eval("(1,2,3)")
>> sage: g in G # error
>>
>> This does not work, to test membership. Unsatisfactory workarounds are:
>>
>> (1) g in G.AsList()
>>
>> works, but for large G this is VERY inefficient ! GAP is of course clever
>> at testing membership.
>>
>> (2) use libgap.eval("G:= SymmetricGroup(3)") then libgap.eval("g:=
>> (1,2,3)") then libgap.eval("g in G")
>>
>> This works, but well, in my real life example G and g are just not built
>> like that.
>>
>> (3) best so far is
>>
>> libgap.set_golobal("G", G)
>> libgap.set_global("g", g)
>> libgap.eval("g in G")
>> libgap.unset_global("G")
>> libgap.unset_global("g)
>>
>> works, but is a bit long !
>>
>> Is there a better way? in particular, is it possible to find the name
>> which G and g must have as variables within GAP? this used to be G.name()
>> with the old GAP interface. Maybe it doesn't make sense anymore.
>>
>> I guess I could write a little GAP_membership(G, g) function,
>> implememting solution (3). It would work in general (eg, verifying whether
>> g is in a given conjugacy class, as returned by G.ConjugacyClasses() ).
>>
>> thanks!
>> Pierre
>>
>>
>>
>>
>>
>>
>>
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