From e268a55680aa4e862c8b75d9b36c2dd8d4a41bdf Mon Sep 17 00:00:00 2001
From: "J.A. de Jong - Redu-Sone B.V., ASCEE V.O.F" <j.a.dejong@ascee.nl>
Date: Thu, 22 Apr 2021 12:10:42 +0200
Subject: [PATCH] Some markup improvements

---
 lasp/filter/biquad.py | 72 +++++++++++++++++++++++--------------------
 1 file changed, 38 insertions(+), 34 deletions(-)

diff --git a/lasp/filter/biquad.py b/lasp/filter/biquad.py
index 912715d..2eb7891 100644
--- a/lasp/filter/biquad.py
+++ b/lasp/filter/biquad.py
@@ -25,9 +25,10 @@ y[n] = 1/ba[3] * (  ba[0] * x[n]   + ba[1] * x[n-1] + ba[2] * x[n-2] +
 __all__ = ['peaking', 'biquadTF', 'notch', 'lowpass', 'highpass',
            'highshelve', 'lowshelve']
 
-from scipy.signal import sosfreqz
+from numpy import array, cos, pi, sin, sqrt
 from scipy.interpolate import interp1d
-from numpy import sin, cos, sqrt, pi, array
+from scipy.signal import sosfreqz
+
 
 def peaking(fs, f0, Q, gain):
     """
@@ -51,6 +52,7 @@ def peaking(fs, f0, Q, gain):
 
     return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0])
 
+
 def notch(fs, f0, Q):
     """
     Notch filter 
@@ -62,14 +64,15 @@ def notch(fs, f0, Q):
     """
     omg0 = 2*pi*f0/fs
     alpha = sin(omg0)/Q/2
-    b0 =   1
-    b1 =  -2*cos(omg0)
-    b2 =   1
-    a0 =   1 + alpha
-    a1 =  -2*cos(omg0)
-    a2 =   1 - alpha
+    b0 = 1
+    b1 = -2*cos(omg0)
+    b2 = 1
+    a0 = 1 + alpha
+    a1 = -2*cos(omg0)
+    a2 = 1 - alpha
     return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0])
 
+
 def lowpass(fs, f0, Q):
     """
     Second order low pass filter 
@@ -81,14 +84,15 @@ def lowpass(fs, f0, Q):
     """
     w0 = 2*pi*f0/fs
     alpha = sin(w0)/Q/2
-    b0 =  (1 - cos(w0))/2
-    b1 =   1 - cos(w0)
-    b2 =  (1 - cos(w0))/2
-    a0 =   1 + alpha
-    a1 =  -2*cos(w0)
-    a2 =   1 - alpha
+    b0 = (1 - cos(w0))/2
+    b1 = 1 - cos(w0)
+    b2 = (1 - cos(w0))/2
+    a0 = 1 + alpha
+    a1 = -2*cos(w0)
+    a2 = 1 - alpha
     return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0])
 
+
 def highpass(fs, f0, Q):
     """
     Second order high pass filter 
@@ -101,12 +105,12 @@ def highpass(fs, f0, Q):
     w0 = 2*pi*f0/fs
     alpha = sin(w0)/Q/2
 
-    b0 =  (1 + cos(w0))/2
+    b0 = (1 + cos(w0))/2
     b1 = -(1 + cos(w0))
-    b2 =  (1 + cos(w0))/2
-    a0 =   1 + alpha
-    a1 =  -2*cos(w0)
-    a2 =   1 - alpha
+    b2 = (1 + cos(w0))/2
+    a0 = 1 + alpha
+    a1 = -2*cos(w0)
+    a2 = 1 - alpha
     return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0])
 
 
@@ -123,14 +127,15 @@ def highshelve(fs, f0, Q, gain):
     w0 = 2*pi*f0/fs
     alpha = sin(w0)/Q/2
     A = 10**(gain/40)
-    b0 =    A*( (A+1) + (A-1)*cos(w0) + 2*sqrt(A)*alpha )
-    b1 = -2*A*( (A-1) + (A+1)*cos(w0)                   )
-    b2 =    A*( (A+1) + (A-1)*cos(w0) - 2*sqrt(A)*alpha )
-    a0 =        (A+1) - (A-1)*cos(w0) + 2*sqrt(A)*alpha
-    a1 =    2*( (A-1) - (A+1)*cos(w0)                   )
-    a2 =        (A+1) - (A-1)*cos(w0) - 2*sqrt(A)*alpha
+    b0 = A*((A+1) + (A-1)*cos(w0) + 2*sqrt(A)*alpha)
+    b1 = -2*A*((A-1) + (A+1)*cos(w0))
+    b2 = A*((A+1) + (A-1)*cos(w0) - 2*sqrt(A)*alpha)
+    a0 = (A+1) - (A-1)*cos(w0) + 2*sqrt(A)*alpha
+    a1 = 2*((A-1) - (A+1)*cos(w0))
+    a2 = (A+1) - (A-1)*cos(w0) - 2*sqrt(A)*alpha
     return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0])
 
+
 def lowshelve(fs, f0, Q, gain):
     """
     Low shelving filter 
@@ -144,14 +149,15 @@ def lowshelve(fs, f0, Q, gain):
     w0 = 2*pi*f0/fs
     alpha = sin(w0)/Q/2
     A = 10**(gain/40)
-    b0 =    A*( (A+1) - (A-1)*cos(w0) + 2*sqrt(A)*alpha )
-    b1 =  2*A*( (A-1) - (A+1)*cos(w0)                   )
-    b2 =    A*( (A+1) - (A-1)*cos(w0) - 2*sqrt(A)*alpha )
-    a0 =        (A+1) + (A-1)*cos(w0) + 2*sqrt(A)*alpha
-    a1 =   -2*( (A-1) + (A+1)*cos(w0)                   )
-    a2 =        (A+1) + (A-1)*cos(w0) - 2*sqrt(A)*alpha
+    b0 = A*((A+1) - (A-1)*cos(w0) + 2*sqrt(A)*alpha)
+    b1 = 2*A*((A-1) - (A+1)*cos(w0))
+    b2 = A*((A+1) - (A-1)*cos(w0) - 2*sqrt(A)*alpha)
+    a0 = (A+1) + (A-1)*cos(w0) + 2*sqrt(A)*alpha
+    a1 = -2*((A-1) + (A+1)*cos(w0))
+    a2 = (A+1) + (A-1)*cos(w0) - 2*sqrt(A)*alpha
     return array([b0/a0, b1/a0, b2/a0, a0/a0, a1/a0, a2/a0])
 
+
 def biquadTF(fs, freq, ba):
     """
     Computes the transfer function of the biquad.
@@ -166,7 +172,5 @@ def biquadTF(fs, freq, ba):
     TODO: This code is not yet tested
     """
     freq2, h = sosfreqz(ba, worN=freq, fs=fs)
-    interpolator = interp1d(freq2, h, kind='quadratic') 
+    interpolator = interp1d(freq2, h, kind='quadratic')
     return interpolator(freq)
-
-