python-control
diff --git a/‎control/config.py‎
Lines changed: 7 additions & 1 deletion b/‎control/config.py‎
Lines changed: 7 additions & 1 deletion
diff --git a/‎control/descfcn.py‎
Lines changed: 3 additions & 2 deletions b/‎control/descfcn.py‎
Lines changed: 3 additions & 2 deletions
@@ -43,9 +43,10 @@ def reset_defaults():
     # System level defaults
     defaults.update(_control_defaults)
 
-    from .freqplot import _bode_defaults, _freqplot_defaults
+    from .freqplot import _bode_defaults, _freqplot_defaults, _nyquist_defaults
     defaults.update(_bode_defaults)
     defaults.update(_freqplot_defaults)
+    defaults.update(_nyquist_defaults)
 
     from .nichols import _nichols_defaults
     defaults.update(_nichols_defaults)
@@ -138,9 +139,11 @@ def use_fbs_defaults():
     The following conventions are used:
         * Bode plots plot gain in powers of ten, phase in degrees,
           frequency in rad/sec, no grid
+        * Nyquist plots use dashed lines for mirror image of Nyquist curve
 
     """
     set_defaults('bode', dB=False, deg=True, Hz=False, grid=False)
+    set_defaults('nyquist', mirror_style='--')
 
 
 # Decide whether to use numpy.matrix for state space operations
@@ -239,4 +242,7 @@ def use_legacy_defaults(version):
         # time responses are only squeezed if SISO
         set_defaults('control', squeeze_time_response=True)
 
+        # switched mirror_style of nyquist from '-' to '--'
+        set_defaults('nyqist', mirror_style='-')
+
     return (major, minor, patch)
@@ -241,8 +241,9 @@ def describing_function_plot(
 
     """
     # Start by drawing a Nyquist curve
-    H_real, H_imag, H_omega = nyquist_plot(H, omega, plot=True, **kwargs)
-    H_vals = H_real + 1j * H_imag
+    count, contour = nyquist_plot(
+        H, omega, plot=True, return_contour=True, **kwargs)
+    H_omega, H_vals = contour.imag, H(contour)
 
     # Compute the describing function
     df = describing_function(F, A)