this routine forms the eigenvectors of a nonsymmetric tridiagonal matrix by back transforming those of the corresponding symmetric matrix

Arnoldi过程是各种大规模计算的一个基本程序，包括计算大规模矩阵的特征值、大规模系统的模型降阶等。(Arnoldi process is a basic algorithm in large-scale computation including eigenvalue solve of matrix and MOR.)