复化梯形公式

复化梯形公式 using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication1 { public class lbg { const int MAXRepeat = 100; public double f(double x)//被积函数,根据自己的需要手工输入 { double s; s = 4.0 / (1 + x * x); return s; } public double Romberg(double a, double b, double epsion) { int m = 1; int n = 1; int k; double h; double ep; double p1; double xk; double p2; double q = 0.0; h = b - a; p1 = 0.5 * h * (f(a) + f(b)); ep = epsion + 1.0; while (ep >= epsion) { p1 = 0.0; for (k = 0; k < n; k++) { xk = a + (k + 0.5) * h; // n-1 p2 = p2+ f(xk); //计算?f(xk+h/2),T } // k=0 p2 = (p1 + h * p) / 2.0; //T`m`(h/2),变步长梯形求积公式 ep = Math.Abs(p2-p1); m++; p1 = p2; n *= 2; // 2 4 8 16 h /= 2.0; } return q; } } class Program { static void Main(string[] args) { lbg l = new lbg(); Console.Write("请输入下界值:"); double x = double.Parse(Console.ReadLine()); Console.Write("请输入上界值:"); double y = double.Parse(Console.ReadLine()); double s = l.Romberg(x, y, 0.000001); Console.Write("积分值为:{0}", s.ToString("0.000000000")); Console.ReadLine(); } } }