Reject inconsistent RTS measurement matrix rows

src/pyrecest/smoothers/rauch_tung_striebel_smoother.py

@@ -123,6 +123,15 @@ def filter(  # pylint: disable=too-many-arguments,too-many-positional-arguments,
             state_dim,
             default=identity_matrix,
         )
+        expected_measurement_matrix_shape = (measurement_dim, state_dim)
+        if any(
+            tuple(matrix.shape) != expected_measurement_matrix_shape
+            for matrix in measurement_matrices_list
+        ):
+            raise ValueError(
+                "measurement_matrices must contain matrices with shape "
+                f"{expected_measurement_matrix_shape}."
+            )
         meas_noise_covariances_list = self._normalize_matrix_sequence(
             meas_noise_covariances,
             len(measurement_list),

tests/smoothers/test_rts_measurement_matrix_shape.py

@@ -0,0 +1,27 @@
+import unittest
+
+from pyrecest.backend import array, eye, zeros
+from pyrecest.distributions import GaussianDistribution
+from pyrecest.smoothers import RauchTungStriebelSmoother
+
+
+class RauchTungStriebelMeasurementMatrixShapeTest(unittest.TestCase):
+    def test_rejects_measurement_matrix_with_wrong_row_count(self):
+        smoother = RauchTungStriebelSmoother()
+
+        with self.assertRaisesRegex(
+            ValueError,
+            r"measurement_matrices must contain matrices with shape \(1, 2\)",
+        ):
+            smoother.filter(
+                initial_state=GaussianDistribution(zeros(2), eye(2)),
+                measurements=array([1.0, 2.0]),
+                measurement_matrices=eye(2),
+                meas_noise_covariances=array([1.0, 1.0]),
+                system_matrices=eye(2),
+                sys_noise_covariances=zeros((2, 2)),
+            )
+
+
+if __name__ == "__main__":
+    unittest.main()