why use svds instead of svd since Ratings_demeaned is not sparse?

[rong1981]

Hi,
In the svd recommender, you got the Ratings_demeaned matrix by R - user_ratings_mean.reshape(-1, 1), actually it's not a sparse matrix (only the original R is), is there any reason for you to use scipy.sparse.linalg.svds to do the decomposition?

thanks,
Terry