利用Gauss积分公式进行数值积分，将区间 细分成n个相等的子区间，然后在每个上使用经过修改适用于不同子区间的三点Gauss公式计算积分的值，然后求和。-Using Gauss integral formula for numerical integration, will be subdivided into n-equal interval sub-intervals, and then apply to each use of a modified three-point range in different sub-Gauss formula to calculate the value of points, and then summed.