Acknowledgments. The authors thank the referees for their helpful comments. The work was supported in part by National Natural Science Foundations of China (No. 10671077, 10971075), Guangdong Provincial Natural Science Foundations (No. 09150631000021, 06025061) and Research Fund for the Doctoral Program of Higher Education of China (No. 20104407110001).
In this paper we consider approximate eigenvalues and approximate eigenspaces for the generalized Rayleigh quotient, and present some residual bounds. Our obtained bounds will improve the existing ones.