diff --git a/Copy_of_EKF_Est_Sim_334.ipynb b/Copy_of_EKF_Est_Sim_334.ipynb
index a935f71..c9e337f 100644
--- a/Copy_of_EKF_Est_Sim_334.ipynb
+++ b/Copy_of_EKF_Est_Sim_334.ipynb
@@ -77,7 +77,8 @@
         "    w = np.linalg.cholesky([[SigmaW]]).T @ np.random.randn(1)\n",
         "    v = np.linalg.cholesky([[SigmaV]]).T @ np.random.randn(1)\n",
         "    ztrue = xtrue.item()**3 + v.item()  # Convert to scalar\n",
-        "    xtrue = np.sqrt(5 + xtrue.item()) + w.item()  # Convert to scalar\n",
+        "    safe_val = max(-5, xtrue.item())\n",
+        "    xtrue = np.sqrt(5 + safe_val) + w.item()  # Convert to scalar\n",
         "\n",
         "    # KF Step 3: Estimate system output\n",
         "    Chat = 3 * xhat**2\n",