diff --git a/Tutorial 03 - PINN Training.ipynb b/Tutorial 03 - PINN Training.ipynb
index 5cecbfd..3b52841 100644
--- a/Tutorial 03 - PINN Training.ipynb	
+++ b/Tutorial 03 - PINN Training.ipynb	
@@ -305,8 +305,6 @@
         "        grad_u_x = grad_u[:, 1]\n",
         "        grad_u_xx = torch.autograd.grad(grad_u_x.sum(), input_int, create_graph=True)[0][:, 1]\n",
         "\n",
-        "        grad_u_sq_x = torch.autograd.grad(u_sq.sum(), input_int, create_graph=True)[0][:,1]\n",
-        "\n",
         "        residual = grad_u_t - grad_u_xx\n",
         "        return residual.reshape(-1, )\n",
         "\n",