demos.optics.ex7.py does not work

[sergey-tomin]

initializing ocelot...
wavelength 1.239841929798582e-10
Traceback (most recent call last):
File "C:/Users/tomins/Documents/Dropbox/DESY/repository/ocelot/demos/optics/ex7.py", line 28, in
w1 = read_signal(file_name='data/pulse_9kev_20fs.txt', npad =10, E_ref = E_ev)
File "C:\Users\tomins\Documents\Dropbox\DESY\repository\ocelot\optics\utils.py", line 54, in read_signal
s.freq_k = -np.roll(s.freq_k, len(spec)/2) + k0 # take into account s/t
File "C:\Users\tomins\AppData\Local\Continuum\Anaconda3\lib\site-packages\numpy\core\numeric.py", line 1398, in roll
res = a.take(indexes, axis)
TypeError: Cannot cast array data from dtype('float64') to dtype('int64') according to the rule 'safe'