In my linear algebra class this summer, I used the Netflix Prize challenge as a pratical example for an application of singular value decomposition (SVD). To be more precise, I explained the term \(p_u^Tq_i\) in the simple SVD with bias model:
The above model can be found in section 2.1 in this progress paper of the winning team. In this note, I will explain this model and give an implementation in Python. A C implementation of the moddel can be found in my GitHub repository here: https://github.com/wormtooth/netflix_svd.