if initial_phase is None:

# Start phase in the range 0 to -360 w/ initial phase = -180

# If wrap_phase is true, use 0 instead (phase \in (-pi, pi])

initial_phase = -math.pi if wrap_phase is not True else 0

initial_phase_value = -math.pi if wrap_phase is not True else 0

elif isinstance(initial_phase, (int, float)):

# Allow the user to override the default calculation

if deg:

initial_phase = initial_phase/180. * math.pi

initial_phase_value = initial_phase/180. * math.pi

else:

initial_phase_value = initial_phase

else:

raise ValueError("initial_phase must be a number.")

# Shift the phase if needed

if abs(phase[0] - initial_phase) > math.pi:

if abs(phase[0] - initial_phase_value) > math.pi:

phase -= 2*math.pi * \

round((phase[0] - initial_phase) / (2*math.pi))

round((phase[0] - initial_phase_value) / (2*math.pi))

# Phase wrapping

if wrap_phase is False:

# Plot the scaled sections of the curve (changing linestyle)

x_scl = np.ma.masked_where(scale_mask, resp.real)

y_scl = np.ma.masked_where(scale_mask, resp.imag)

plt.plot(

x_scl * (1 + curve_offset), y_scl * (1 + curve_offset),

primary_style[1], color=c, **kwargs)

if x_scl.count() >= 1 and y_scl.count() >= 1:

plt.plot(

x_scl * (1 + curve_offset),

y_scl * (1 + curve_offset),

primary_style[1], color=c, **kwargs)

# Plot the primary curve (invisible) for setting arrows

x, y = resp.real.copy(), resp.imag.copy()

# Plot the regular and scaled segments

plt.plot(

x_reg, -y_reg, mirror_style[0], color=c, **kwargs)

plt.plot(

x_scl * (1 - curve_offset),

-y_scl * (1 - curve_offset),

mirror_style[1], color=c, **kwargs)

if x_scl.count() >= 1 and y_scl.count() >= 1:

plt.plot(

x_scl * (1 - curve_offset),

-y_scl * (1 - curve_offset),

mirror_style[1], color=c, **kwargs)

# Add the arrows (on top of an invisible contour)

x, y = resp.real.copy(), resp.imag.copy()