Merge branch '44-rescale-one-sided-spectrum-in-ifft_generator' into 'master'

Resolve "Rescale one-sided spectrum in `ifft_generator`"

Closes #44

See merge request !50

lisagwresponse/psd.py

@@ -25,7 +25,7 @@ def white_generator(psd):
         simulation size [samples].
     """
     def generator(fs, size):
-        stddev = np.sqrt(psd * fs / 4)
+        stddev = np.sqrt(psd * fs / 2)
         return np.random.normal(scale=stddev, size=size)
     return generator
 

tests/test_psd.py

+#! /usr/bin/env python3
+# -*- coding: utf-8 -*-
+# pylint: disable=missing-module-docstring
+
+import numpy as np
+from scipy.signal import welch
+from lisagwresponse.psd import white_generator, ifft_generator
+
+
+def test_white_generator():
+    """Test that white generator generates a white noise."""
+
+    size = 100000
+
+    for fs in [1.0, 0.2, 10.0]:
+        for psd in [1.0, 0.1, 12.3, 42.0]:
+
+            generator = white_generator(psd)
+            data = generator(fs, size)
+            data_psd = welch(data, fs, nperseg=size // 100)[1][5:-5]
+
+            assert np.isclose(np.mean(data), 0.0, atol=0.1)
+            assert np.all(np.isclose(data_psd, psd, rtol=0.5))
+
+def test_ifft_generator_white():
+    """Test that IFFT generator can generate a white noise."""
+
+    size = 100000
+
+    for fs in [1.0, 0.2, 10.0]:
+        for psd in [1.0, 0.1, 12.3, 42.0]:
+
+            generator = ifft_generator(lambda _: psd) # pylint: disable=cell-var-from-loop
+            data = generator(fs, size)
+            data_psd = welch(data, fs, nperseg=size // 100)[1][5:-5]
+
+            assert np.isclose(np.mean(data), 0.0, atol=0.1)
+            assert np.all(np.isclose(data_psd, psd, rtol=0.5))