Small changes on eig_symm.py, speed related. 

Math is way faster than numpy for single scalars.
Try the following on a ipython terminal:

>>>timeit math.sin(1)
1000000 loops, best of 3: 566 ns per loop

>>>timeit np.sin(1)
1 loops, best of 3: 15 us per loop

The change to the test matrix was just personal taste. Anyway, is a good implementation of Smith 1961. By the way, do you happen to have any better reference than smith for this?
Thanks for your attention