diff --git a/ex8/cofiCostFunc.m b/ex8/cofiCostFunc.m
index 37f4bfd..02d14a6 100644
--- a/ex8/cofiCostFunc.m
+++ b/ex8/cofiCostFunc.m
@@ -42,6 +42,8 @@ Theta_grad = zeros(size(Theta));
 
 J = 0.5 * sum(sum(R.*(X*Theta'-Y).^2));
 
+X_grad = (R.*(X*Theta'-Y))*Theta;  % mov X user * uxer X feat = mov X feat
+Theta_grad = (R.*(X*Theta'-Y))'*X;  % user X mov * mov X feat = user X feat
 
 % =============================================================