A preconditioned Newton algorithm for the nearest correlation matrix

A preconditioned Newton algorithm for the nearest correlation matrix

Various methods have been developed for computing the correlation matrix nearest in the Frobenius norm to a given matrix. We focus on a quadratically convergent Newton algorithm recently derived by Qi and Sun. Various improvements to the efficiency and reliability of the algorithm are introduced. Several of these relate to the linear algebra: the Newton equations are solved by minres instead of...

A Sequential Semismooth Newton Method for the Nearest Low-rank Correlation Matrix Problem

Based on the well-known result that the sum of the largest eigenvalues of a symmetric matrix can be represented as a semidefinite programming problem (SDP), we formulate the nearest low-rank correlation matrix problem as a nonconvex SDP and propose a numerical method that solves a sequence of least-square problems. Each of the least-square problems can be solved by a specifically designed semis...

A Quadratically Convergent Newton Method for Computing the Nearest Correlation Matrix

The nearest correlation matrix problem is to find a correlation matrix which is closest to a given symmetric matrix in the Frobenius norm. The well-studied dual approach is to reformulate this problem as an unconstrained continuously differentiable convex optimization problem. Gradient methods and quasi-Newton methods such as BFGS have been used directly to obtain globally convergent methods. S...

Computing the Nearest Correlation Matrix using Difference Map Algorithm

The difference map algorithm (DMA) is originally designed to find the global optimal solution to nonconvex problems. The main feature of DMA is that it can avoid the stagnation, (which always occurs when applying the alternating projection method (APM) on nonconvex problems so that APM is trapped at local minimized point and fail to find the global optimal solution.) and converge to the global ...

Computing the Nearest Correlation Matrix