This directory contains MATLAB code for the examples in H.-H. Chao and L. Vandenberghe, Entropic Proximal Operators for Nonnegative Trigonometric Polynomials, to appear in IEEE Transactions on Signal Processing. example1.m: covariance fitting example2.m: projection on cone of nonnegative trigonometric example ISproj.m: entropy projection toeplitzFact.m: Levinson algorithm qmeif.m, qmef.m: structured positive semidefinite matrix factorization The code requires CVX (cvxr.com).