Weihua Luo was born in Hunan province in 1982. PhD in School of Mathematical Sciences, University of Electronic Science and Technology of China, Chengdu. The author's major field is numerical algebra and scientific computation.He once worked as a teacher in Neijiangnormal university in Sichuan province. So far, he has publishedtwo papers in Applied Mathematics and Computation, Journal of Applied Mathematics. Nowadays, he is being interested in preconditioning techniques for large sparse linear systems. Tingzhu Huang was born in Sichuan province in 1964. Doctoral supervisor in School of Mathematical Sciences, University of Electronic Science and Technology of China, Chengdu. His major field is numerical algebra and scientific computation.