I was experimenting with the perperiodic cyclegraph code and came across
something with the ComplexIntervalField. Just to get some interesting
points I computed the QQ-rational preperiodic points for a function and
simply moved them around with change_ring() and recreated the associated
DiGraph.
P.<x,y>=ProjectiveSpace(QQ,1)
H=End(P)
f = H([-3/2*x^3 +19/6*x*y^2,y^3])
g=f.rational_preperiodic_points(prime_bound=[1,8])
K=ComplexIntervalField()
F=f.change_ring(K)
G=[p.change_ring(K) for p in g]
D={}
for t in G:
D.update({t:[F(t)]})
DiGraph(D)
For ComplexIntervalField and RealIntervalField it is getting 18 vertices
instead of 12, but if you compare the vertices against each other (==)
there are still only 12 that are distinct. hmm...that description was not
very clear, let me try again. It seems that when DiGraph is compiling its
list of vertices for CIF, it is treating two values which are == as two
different vertices so is producing the 'wrong' DiGraph (based on ==). I
hesitate to file a bug here as I'm not 100% conversant with what CIF is
doing with ==. Could someone familiar with DiGraph take a look at the
example I've included to verify that this is not expected behavior. If it
is not, it is probably worth checking QQbar as well, although you'll need a
different example.
Thanks.
Ben
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