求解大规模对称矩阵的CG算法，及预处理PCG使用Matlab语言，可以解1000阶以上的矩阵，以病态矩阵hilbert为例,Solving large-scale symmetric matrix of the CG algorithm, and pretreatment of PCG using Matlab language, you can order more than 1,000 solution matrix, as an example to pathological matrix