说明：  上传的文件对数值分析课本里 Lagrange插值，Newton插值，三次样条差值，复合梯形公式和复合辛普森公式积，龙贝格算法，高斯消去法，LU分解，改进欧拉法MATLAB编程，并画出图形。
(Upload the file to the numerical analysis textbook Lagrange interpolation, Newton interpolation, three times spline interpolation, the composite trapezoidal formula and Simpson formula of composite product, Romberg algorithm, decomposition of LU Gauss elimination method, the improved Euler method, MATLAB programming, and draw the graph. )