摘要：We present new iterative methods based on refinement process for solving large sparse Sylvester-observer
equations applied in state estimation of a continuous-time system. These methods use projection methods to produce low-dimensional Sylvester-observer matrix equations that are solved by the direct methods. Moreover, the refinement process
described in this paper has the capability of improving the results obtained by any other methods. Some numerical results
will be reported to illustrate the efficiency of the proposed methods.
