docs: def _make_tonnetz_matrix():
      """Return the tonnetz projection matrix."""
      pi = np.pi
      chroma = np.arange(12)
  
      # Define each row of the transform matrix
      fifth_x = r_fifth*(np.sin((7*pi/6) * chroma))
      fifth_y = r_fifth*(np.cos((7*pi/6) * chroma))
      minor_third_x = r_minor_thirds*(np.sin(3*pi/2 * chroma))
      minor_third_y = r_minor_thirds*(np.cos(3*pi/2 * chroma))
      major_third_x = r_major_thirds*(np.sin(2*pi/3 * chroma))
      major_third_y = r_major_thirds*(np.cos(2*pi/3 * chroma))
  
      # Return the tonnetz matrix
      return np.vstack((fifth_x, fifth_y,
                        minor_third_x, minor_third_y,
                        major_third_x, major_third_y))