linear problems的用法和样例：
例句
- Both methods result in tridiagonal systems of linear equations that can be solved efficiently.
两种方法都形成了有效求解的三对角线的线性方程组。 - The numerical results of some test problems show that the two-grid methods are robust in solving regularized systems.
试验问题的数值结果表明，双网格迭代方法求解正则化后的对称正定线性方程组效果很好。
