对称线性方程 meaning in English

symmetric linear equations
symmetrical linear equation

This paper mainly studies the backward perturbation methods in solving the linear systems , and total minimal backward perturbation ( tminback ) method for symmetric linear systems is presented
本文研究了求解线性方程组的向后扰动方法。对求解对称线性方程组的lanczos方法做出了向后扰动分析，给出了求解对称线性方程组的总体极小向后扰动( tminback )方法。
The deflated restarted total minimization backward perturbation method ( drtminback ) is presented . when solving the nonsymmetric linear systems , the paper makes the total backward perturbation analysis to qmr method , and uses the total quasi - minimal backward perturbation ( tqmback ) technique . so the restarted total quasi - minimal backward perturbation ( rtqmback ) method is given
同样地，对求解非对称线性方程组的qmr方法作出了向后扰动分析，结合总体向后扰动范数拟极小化的技巧，给出了求解非对称线性方程组的总体拟极小向后扰动( tqmback )方法。