Linearly Convergent Randomized Iterative Methods for Computing the Pseudoinverse
This work provides efficient randomized algorithms for pseudoinverse computation, a fundamental linear algebra operation, benefiting large-scale machine learning and optimization applications.
The paper introduces the first stochastic incremental methods for computing the Moore-Penrose pseudoinverse, with linear convergence guarantees, and demonstrates that these methods significantly outperform the Newton-Schulz method on large matrices.
We develop the first stochastic incremental method for calculating the Moore-Penrose pseudoinverse of a real matrix. By leveraging three alternative characterizations of pseudoinverse matrices, we design three methods for calculating the pseudoinverse: two general purpose methods and one specialized to symmetric matrices. The two general purpose methods are proven to converge linearly to the pseudoinverse of any given matrix. For calculating the pseudoinverse of full rank matrices we present two additional specialized methods which enjoy a faster convergence rate than the general purpose methods. We also indicate how to develop randomized methods for calculating approximate range space projections, a much needed tool in inexact Newton type methods or quadratic solvers when linear constraints are present. Finally, we present numerical experiments of our general purpose methods for calculating pseudoinverses and show that our methods greatly outperform the Newton-Schulz method on large dimensional matrices.