in cost function formula ,we added regularization at the end
what does (n) in summation refer to ?
another questions :
Does cost function formula calculate the cost of user(J) for all movies watched[=Rated]?
Does Wj is the same for all movies user rated ?
Hey @MOHAMED_AZIZ2,
Let’s address your question:

The “n” dentoes the number of training examples or data points in your dataset. It represents the size of your training dataset.

The cost function is a measure of how well a recommendation system’s predictions match the actual ratings or preferences of users for movies or items.
It calculates the overall error or cost associated with the predictions made by the recommendation system for all the movies that users have rated.

No, the weights Wj are not necessarily the same for all movies a user has rated. In many recommendation algorithms, such as collaborative filtering, the weights can vary based on the movie or item and are often used to handle situations where some ratings are more reliable or informative than others.
Regards,
Jamal
thanks, bro
for this information and Simplified explanation