diff --git a/frc971/control_loops/python/controls.py b/frc971/control_loops/python/controls.py
index 4cb10a2..7c7c310 100644
--- a/frc971/control_loops/python/controls.py
+++ b/frc971/control_loops/python/controls.py
@@ -85,11 +85,11 @@
     J = sum(0, inf, x.T * Q * x + u.T * R * u)
   """
 
-    # P = (A.T * P * A) - (A.T * P * B * numpy.linalg.inv(R + B.T * P *B) * (A.T * P.T * B).T + Q
-    # 0.5 * X.T * P * X -> optimal cost to infinity
+    # P = (A.T * P * A) - (A.T * P * B * numpy.linalg.inv(R + B.T * P * B) * (A.T * P.T * B).T + Q
+    # X.T * P * X -> optimal cost to infinity
 
     P = scipy.linalg.solve_discrete_are(a=A, b=B, q=Q, r=R)
-    F = numpy.linalg.inv(R + B.T * P * B) * B.T * P * A
+    F = numpy.linalg.inv(R + B.T @ P @ B) @ B.T @ P @ A
     if optimal_cost_function:
         return F, P
     else:
diff --git a/y2018/control_loops/python/extended_lqr.py b/y2018/control_loops/python/extended_lqr.py
index e19ee8f..a2a31af 100755
--- a/y2018/control_loops/python/extended_lqr.py
+++ b/y2018/control_loops/python/extended_lqr.py
@@ -85,6 +85,7 @@
     Returns:
       numpy.matrix(1, 1), The quadratic cost of being at X
     """
+        print('TODO(austin): S -> X.T * S * X, need to fix if we care')
         return 0.5 * X.T * self.S * X
 
     def cost(self, X, U):