From 0ef95a3336bcad3baa401a6505b160090efe053b Mon Sep 17 00:00:00 2001
From: marko1olo <barsukdana@gmail.com>
Date: Mon, 8 Jun 2026 10:09:12 +0400
Subject: [PATCH] Preserve complex StateSpace matrices

---
 control/statesp.py            |  3 ++-
 control/tests/statesp_test.py | 18 +++++++++++++++++-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/control/statesp.py b/control/statesp.py
index 65529b99d..edde5c411 100644
--- a/control/statesp.py
+++ b/control/statesp.py
@@ -2302,7 +2302,8 @@ def _ssmatrix(data, axis=1, square=None, rows=None, cols=None, name=None):
     name = "" if name is None else " " + name
 
     # Convert the data into an array (always making a copy)
-    arr = np.array(data, dtype=float)
+    dtype = complex if np.iscomplexobj(data) else float
+    arr = np.array(data, dtype=dtype)
     ndim = arr.ndim
     shape = arr.shape
 
diff --git a/control/tests/statesp_test.py b/control/tests/statesp_test.py
index 9b3c677fe..9c38135d9 100644
--- a/control/tests/statesp_test.py
+++ b/control/tests/statesp_test.py
@@ -8,6 +8,7 @@
 """
 
 import operator
+import warnings
 
 import numpy as np
 import pytest
@@ -136,7 +137,6 @@ def test_constructor(self, sys322ABCD, dt, argfun):
          ((np.ones((3, 3)), np.ones((3, 2)),
            np.ones((2, 3)), np.ones((2, 3))), ValueError,
           r"Incompatible dimensions of D matrix; expected \(2, 2\)"),
-         (([1j], 2, 3, 0), TypeError, "real number, not 'complex'"),
         ])
     def test_constructor_invalid(self, args, exc, errmsg):
         """Test invalid input to StateSpace() constructor"""
@@ -146,6 +146,22 @@ def test_constructor_invalid(self, args, exc, errmsg):
         with pytest.raises(exc, match=errmsg):
             ss(*args)
 
+    def test_constructor_complex_matrices(self):
+        """Test complex-valued matrices in StateSpace() constructor"""
+        A = np.array([[1 + 1j, 2 - 3j], [3 + 2j, 4 - 1j]])
+        B = np.array([[1 - 2j], [3 + 4j]])
+        C = np.array([[5 + 6j, 7 - 8j]])
+        D = np.array([[9 + 10j]])
+
+        with warnings.catch_warnings():
+            warnings.simplefilter("error")
+            sys = StateSpace(A, B, C, D)
+
+        np.testing.assert_allclose(sys.A, A)
+        np.testing.assert_allclose(sys.B, B)
+        np.testing.assert_allclose(sys.C, C)
+        np.testing.assert_allclose(sys.D, D)
+
     def test_constructor_warns(self, sys322ABCD):
         """Test ambiguos input to StateSpace() constructor"""
         with pytest.warns(UserWarning, match="received multiple dt"):