Robert Granat and Bo Kågström
Department of Computing Science and HPC2N,
Umeå University, SE-901 87 Umeå, Sweden.
emails: {granat,bokg}@cs.umu.se
Recent ScaLAPACK-style implementations of the Bartels-Stewart method [1, 4, 5] and a parallel implementation of an iterative matrix-sign- function-based method [2, 3] for solving continuous-time Sylvester matrix equations are evaluated with respect to generality of use, execution time and accuracy of computed results. The test problems include well-conditioned as well as ill-conditioned Sylvester equations. Experiments carried out on two different distributed memory machines show that the parallel explicitly blocked Bartels-Stewart algorithm can solve more general problems and delivers far more accuracy for ill-conditioned problems. It is also up to four times faster for large enough problems on the most balanced parallel platform (IBM SP), while the parallel iterative algorithm is almost always the fastest of the two on the less balanced platform (HPC2N Linux Super Cluster).
References:
[1]R.H. Bartels and G.W. Stewart,
"Algorithm 432: Solution of the Equation
",
Comm. ACM, 15(9):820-826.
[2]P. Benner, E.S. Quintana-Orti,
"Solving Stable Generalized Lyapunov Equations with the matrix sign
functions", Numerical Algorithms, 20 (1), pp. 75-100, 1999.
[3]P. Benner, E.S. Quitana-Orti, G. Quintana-Orti,
"Numerical Solution of Discrete Schur Stable Linear Matrix Equations on
Multicomputers", Parallel Alg. Appl, Vol. 17, No. 1, pp. 127-146, 2002.
[4]R. Granat, "A Parallel ScaLAPACK-style Sylvester Solver",
Master Thesis, UMNAD 435/03, Dept. Computing Science,
Umeå University, Sweden, January, 2003.
[5]R. Granat, B. Kågström, P. Poromaa,
"Parallel ScaLAPACK-style Algorithms for Solving Continous-Time
Sylvester Equationsr", In H. Kosch et al., Euro-Par 2003 Parallel Processing.
Lecture Notes in Computer Science, Vol. 2790, pp. 800-809, 2003.