fluctuation_diff

def fluctuation_diff(x, y, section_lengthx,section_lengthy, num_steps, number_lignes,number_sections,num_particles_insection_data):
    fluctuation_diff = np.zeros((number_sections, num_steps))
    for delta in range(1,num_steps):
        nt0 = 0
        for t0 in range (0, num_steps-delta):
            fluctuation_t0 = num_particles_insection_data[:,t0]
            fluctuation_t = num_particles_insection_data[:,t0 + delta]
            fluctuation_diff[:,delta] += (fluctuation_t - fluctuation_t0)**2
            nt0 += 1
        fluctuation_diff[:,delta] /= nt0
    return fluctuation_diff
diff=fluctuation_diff(x, y, section_lengthx,section_lengthy, num_steps, number_lignes,number_sections,num_particles_insection_data)
def computational_msd(diff, num_steps):
    computational_displacement = np.zeros(num_steps)
    for t in range(num_steps):
        computational_displacement[t] = np.mean(diff[:, t])
    return computational_displacement