求解大型稀疏方程组的全选主元高斯-约当消去法--返回零表示原方程组的系数矩阵奇异，返回的标志值不为零，则表示正常返回。-solving large sparse linear system-wide elections PCA Gauss-Jordan elimination method -- to return to the original equation is expressed by the coefficient matrix, a sign of the return value