David,
I am trying the fix the doctests bug in sage/graphs/generic_graph.py
where M is assigned the character table of a group.
Obviously det(M) can only be correct up to a sign, as we have no
control over the
order of rows and/or columns of M.
So this is actually a doctests-specific probem: if I
Robert,
I don't understand what you suggest.
Try the following:
replace the line 10222 of sage/graphs/generic_graph.py
with
sage: abs(M.determinant())
(the original line does not have abs()) and run
sage -t -long devel/sage/sage/graphs/generic_graph.py
You should see the result above.
On Feb 2, 7:03 pm, Dima Pasechnik dimp...@gmail.com wrote:
Robert,
I don't understand what you suggest.
Try the following:
replace the line 10222 of sage/graphs/generic_graph.py
with
sage: abs(M.determinant())
(the original line does not have abs()) and run
sage -t -long
On Tue, 2 Feb 2010 19:40:11 -0800 (PST), John H Palmieri
jhpalmier...@gmail.com wrote:
sage: C = graphs.CubeGraph(4)
sage: G = C.automorphism_group()
sage: M = G.character_table()
sage: M.determinant()
-712483534798848
sage: parent(M.determinant())
Cyclotomic Field of order 1 and degree 1
On Feb 2, 2010, at 7:40 PM, John H Palmieri wrote:
On Feb 2, 7:03 pm, Dima Pasechnik dimp...@gmail.com wrote:
Robert,
I don't understand what you suggest.
Try the following:
replace the line 10222 of sage/graphs/generic_graph.py
with
sage: abs(M.determinant())
(the original line does not
sage: d = M.determinant()
sage: d.norm().abs() # take norm to get an integer
712483534798848
I thought of this as well, but it could be wrong since there might be
an element of the appropriate norm in the cyclotomic field that is
erroneously returned! I suggest QQ(d).abs() :)
Nick
it looks OK just to coerse to integer and then do the python's abs:
ZZ(d).abs()
By the way, the determinant of a character table is either in Z or in
sqrt(-1)Z
DIma
On Feb 3, 12:34 pm, Nick Alexander ncalexan...@gmail.com wrote:
sage: d = M.determinant()
sage: d.norm().abs() # take
On Tue, 2 Feb 2010 20:34:58 -0800, Nick Alexander ncalexan...@gmail.com wrote:
sage: d = M.determinant()
sage: d.norm().abs() # take norm to get an integer
712483534798848
I thought of this as well, but it could be wrong since there might be
an element of the appropriate norm in
By the way, the determinant of a character table is either in Z or in
sqrt(-1)Z
oops, I meant to say that the square of the determinant of a character
table
is a positive integer
(namely, the sum of the orders of the centralisers of representatives
of conjugacy classes)
Dima
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