R package recosystem. R wrapper of the ’libmf’ library (http://www.csie.ntu.edu.tw/ cjlin/libmf/) for recommender system using matrix factorization. It is typically used to approximate an incomplete matrix using the product of two matrices in a latent space. Other common names for this task include ”collaborative filtering”, ”matrix completion”, ”matrix recovery”, etc. High performance multi-core parallel computing is supported in this package.