Table 3: Implementation of new Iterative methods with 2 iterations and the Hessenberg-Schur method for solving the Sylvester equation.

Hessenberg-Schur methodBlock refinementWeighted block refinementCond ( )
ErrorTimeErrorTimeErrorTime

400 4.84 3.58 1.81
800 61.89 48.24 32.11
1200 11.01 139.54 0.043 96.25 71.43
1600 26.29 208.24 11.01 134.32 112.55
2000 71.98 347.14 39.91 242.11 194.78