Fix psd

This should resolve https://git.ligo.org/Monash/tupak/issues/103.

frequency_noise_realization is not doing anything -> The intended functionality lives in get_noise_realisation (I think).

interpolated_frequency is not doing anything either and I am not sure what this is supposed to be doing.

These have been removed

amplitude_spectral_density and power_spectral_density are related by a power of 2. We can implement this as a @property to avoid redundant logic in import_amplitude_spectral_density and import_power_spectral_density.

These are now properties and the setters update the other.

import_amplitude_spectral_density and import_power_spectral_density contain a lot of similar logic that should probably go in a separate static helper method.

I think these are a little simpler now. I also got rid of the _set_... functions.

interpolate_power_spectral_density could reasonably be implemented as an @property or power_spectral_density_interpolated -> I would check beforehand how often this is called and what performance impact it has.

I want to leave this as it is. This interpolation method has been given an underscore to dissuade people from calling it. I'm wary of having interpolation things as properties.

test/noise_realisation_tests.py

@@ -8,7 +8,7 @@ class TestNoiseRealisation(unittest.TestCase):
     def test_averaged_noise(self):
         time_duration = 1.
         sampling_frequency = 4096.
-        factor = np.sqrt(2./time_duration)
+        factor = np.sqrt(2 / time_duration)
         n_avg = 1000
         psd_avg = 0
         interferometer = tupak.gw.detector.get_empty_interferometer('H1')
@@ -16,11 +16,12 @@ class TestNoiseRealisation(unittest.TestCase):
             interferometer.set_data(sampling_frequency, time_duration, from_power_spectral_density=True)
             psd_avg += abs(interferometer.data)**2
 
-        psd_avg = psd_avg/n_avg
-        asd_avg = np.sqrt(abs(psd_avg))
+        psd_avg = psd_avg / n_avg
+        asd_avg = np.sqrt(abs(psd_avg)) * interferometer.frequency_mask
 
-        a = interferometer.amplitude_spectral_density_array/factor
+        a = np.nan_to_num(interferometer.amplitude_spectral_density_array / factor * interferometer.frequency_mask)
         b = asd_avg
+        print(a, b)
         self.assertTrue(np.allclose(a, b, rtol=1e-1))
 
     def test_noise_normalisation(self):