--- a
+++ b/devel/bug_rlocus.m
@@ -0,0 +1,7 @@
+## bug #41820: control package: rlocus errors on input when max_k is not specified for some input
+##
+## https://savannah.gnu.org/bugs/?41820
+
+graphics_toolkit gnuplot
+figure
+rlocus (tf ([1, 4, 4], [1, 8, 1, 8, 0]))