Add exploration of linear interp filter freq response

filters/lerp.py

@@ -0,0 +1,34 @@
+import matplotlib.pyplot as plt
+import numpy as np
+
+from scipy import signal
+
+f, (ax1, ax2) = plt.subplots(2, sharex=True)
+
+for i in np.linspace(0.0, 1.0, 11):
+    # A linear interpolation filter with a factor of `i`.
+    w, h = signal.freqz([(1.0 - i), i])
+
+    # Scale x-axis to Hz.
+    x = w * 44100 / (2 * np.pi)
+
+    # Plot amplitude response on the dB scale.
+    ax1.plot(x,  20 * np.log10(abs(h)), color='c', alpha=1.0 - i)
+
+    # Plot phase response in radians.
+    ax2.plot(x, np.unwrap(np.angle(h)), color='c', alpha=1.0 - i)
+
+ax1.set_title('Amplitude Response (dB)')
+ax2.set_title('Phase Response (radians)')
+
+ax2.set_yticks(np.linspace(-1.0, 0.0, 5) * np.pi)
+ax2.set_yticklabels([r'$-\pi$', r'$-\frac{3\pi}{4}$', r'$-\frac{\pi}{2}$',
+    r'$-\frac{\pi}{4}$', r'$0$'])
+
+ax1.axis('tight')
+ax2.axis('tight')
+
+ax1.grid()
+ax2.grid()
+
+plt.show()