m is an integer matrix and its eigenvalues (which are not all rel
anyway) are returned as algebraic numbers (try e[0].parent()).

Perhaps you want this:
sage: max([RR(ei) for ei in e if ei in RR])
1.99801167774722

but note that only 22 of the 38 eigenvalues are real.

John


On 30 March 2014 14:32, Paul Mercat <merc...@yahoo.fr> wrote:
> The function max sometimes doesn't work in sage.
> Here is an example :
>
> sage: a = Automaton([(0, 0, 0), (0, 1, 1), (1, 1, 1), (1, 2, 0), (2, 0, 0),
> (2, 3, 1), (3, 4, 1), (3, 7, 0), (4, 1, 1), (4, 5, 0), (5, 0, 0), (5, 6, 1),
> (6, 7, 0), (6, 37, 1), (7, 3, 1), (7, 8, 0), (8, 0, 0), (8, 9, 1), (9, 2,
> 0), (9, 10, 1), (10, 2, 0), (10, 11, 1), (11, 2, 0), (11, 12, 1), (12, 13,
> 0), (12, 34, 1), (13, 14, 0), (13, 24, 1), (14, 1, 1), (14, 15, 0), (15, 16,
> 0), (15, 33, 1), (16, 0, 0), (16, 17, 1), (17, 1, 1), (17, 18, 0), (18, 3,
> 1), (18, 19, 0), (19, 1, 1), (19, 20, 0), (20, 1, 1), (20, 21, 0), (21, 22,
> 0), (21, 31, 1), (22, 23, 0), (23, 0, 0), (23, 24, 1), (24, 4, 1), (24, 25,
> 0), (25, 26, 1), (25, 29, 0), (26, 7, 0), (26, 27, 1), (27, 1, 1), (27, 28,
> 0), (28, 6, 1), (28, 19, 0), (29, 0, 0), (29, 30, 1), (30, 10, 1), (30, 18,
> 0), (31, 2, 0), (31, 32, 1), (32, 2, 0), (32, 3, 1), (33, 2, 0), (33, 17,
> 1), (34, 35, 1), (35, 1, 1), (35, 36, 0), (36, 16, 0), (36, 26, 1), (37, 5,
> 0), (37, 11, 1)])
> sage: m = a.graph().adjacency_matrix()
> sage: e = m.eigenvalues()
> sage: print e
> sage: max(e) #doesn't terminate !!!
>
> Do you know why it doesn't work ?
>
> Paul
>
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