Masaaki Kanno Kazuhiro Yokoyama Hirokazu Anai Shinji Hara Parametric optimization in control using the sum of roots for parametric polynomial spectral factorization. 211-218 2007 conf/issac/2007 ISSAC http://doi.acm.org/10.1145/1277548.1277578 db/conf/issac/issac2007.html#KannoYAH07