调用方法： CurveFitting fitting = new CurveFitting() double[] xs = fitting.Fitting(xv, yv, n, m) 说明： 拟合函数：double[] xs=Fitting(int[] xval, double[] val, int n, int m) xval:点的横坐标 val:点的纵坐标值 n:欲拟合多项式的最高次数 m:拟合点的个数 数组xs为返回的多项式系数，次数从0到n。如有问题，请发送邮件至ga

利用颤振导数拟合，拟合出阶跃函数的系数，用于时域分析-Flutter derivatives utilizing fitting, fitting step function coefficients, time domain analysis is used