diff --git a/control/freqplot.py b/control/freqplot.py
index 3bc3a0c24..456431f38 100644
--- a/control/freqplot.py
+++ b/control/freqplot.py
@@ -1447,6 +1447,12 @@ def nyquist_response(
else:
contour = np.exp(splane_contour * sys.dt)
+ # Make sure we don't try to evaluate at a pole
+ if isinstance(sys, (StateSpace, TransferFunction)):
+ if any([pole in contour for pole in sys.poles()]):
+ raise RuntimeError(
+ "attempt to evaluate at a pole; indent required")
+
# Compute the primary curve
resp = sys(contour)
diff --git a/control/tests/nyquist_test.py b/control/tests/nyquist_test.py
index 0d6907b64..8d6fd8561 100644
--- a/control/tests/nyquist_test.py
+++ b/control/tests/nyquist_test.py
@@ -517,6 +517,15 @@ def test_nyquist_frd():
warnings.resetwarnings()
+def test_no_indent_pole():
+ s = ct.tf('s')
+ sys = ((1 + 5/s)/(1 + 0.5/s))**2 # Double-Lag-Compensator
+
+ with pytest.raises(RuntimeError, match="evaluate at a pole"):
+ resp = ct.nyquist_response(
+ sys, warn_encirclements=False, indent_direction='none')
+
+
if __name__ == "__main__":
#
# Interactive mode: generate plots for manual viewing
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