 The FastProjectedNewton file provides the implementation of the FPN method [1]. The main function is solver_fpn.

 [1] Cai, J.-F., Cardoso, J. V. d. M., Palomar, D. P., and Ying, J. Fast projected Newton-like method for precision matrix estimation under total positivity. arXiv e-prints, pp. arXiv–2112, 2021

 