Convex Algorithms for Nonnegative Matrix Factorization
  We derive approximation algorithms for the nonnegative matrix factorization problem, i.e. the problem of factorizing a matrix as the product of two matrices with nonnegative coefficients. We form convex approximations of this problem which can be solved efficiently and test our algorithms on some classic numerical examples. 
Vijay Krishnamurthy, Alexandre d'Aspremont
math.OC