2011/04/09 by Guruswami, Venkatesan, Sinop, Ali Kemal
#Data Structures and Algorithms (cs.DS) #FOS: Computer and information sciences #FOS: Mathematics #Spectral Theory (math.SP)
paper · doi:10.48550/arxiv.1104.1732
We prove that for any real-valued matrix X ∈ \Rm × n, and positive integers r ≥ k, there is a subset of r columns of X such that projecting X onto their span gives a √((r+1)/(r-k+1))-approximation to best rank-k approximation of X in Frobenius norm. We show that the trade-off we achieve between the number of columns and the approximation ratio is optimal up to lower order terms. Furthermore, there is a deterministic algorithm to find such a subset of columns that runs in O(r n mω log m) arithmetic operations where ω is the exponent of matrix multiplication. We also give a faster randomized algorithm that runs in O(r n m2) arithmetic operations.