Well... the nonnegative matrix factorization builds a basis for the column space where all entries of the basis vectors are positive. This might be meaningful i

Well... the nonnegative matrix factorization builds a basis for the column space where all entries of the basis vectors are positive. This might be meaningful if the entries are thought of as some positive quantity like weight or energy. In the SVD the basis vectors for the column space consist of entries that are not necessarily positive.