关键词：双共轭梯度法;有限精度运算;S-级多项式
摘 要：We analyze the s-step biconjugate gradient algorithm in nite precision arithmetic and derive a bound for the residual norm in terms of a minimum polynomial of a perturbed matrixmultiplied by an ampli cation factor. Our bound enables comparison of s-step and classical biconjugate gradient in terms of ampli cation factors. Our results show that for s-step biconjugate gradient, the ampli cation factor depends heavily on the quality of s-step polynomial bases generated in each outer loop.