对1/(1+x^2) 进行0到1的积分即使pi/4;
采用simpson方法
Func<double,double> func=(x)=>{ return 1/(1+ Math.Pow(x,2) ) ;};
var n = 1000; double h = 1.0d / n; double sumx = 0; double sum = func(0.0);for (int i = 1; i < n; i++)
{ sumx += h; var factor = ((i % 2) == 1) ? 4 : 2; //Console.WriteLine(i +":" + factor +"," + sumx); sum +=factor * func(sumx); } sum += func(1); var v = 4* (sum * h) / 3; Console.WriteLine(v);