niudun.rar_c++积分函数

#include <iostream> #include <cstring> #include <cmath> using namespace std; //const int MAX_LEN = 100; double Function(double x) { return x * x + log(x); } double Rate(double x) { const double deltaX = 1E-6; double y1 = Function(x - deltaX); double y2 = Function(x + deltaX); return (y2 - y1) / 2 / deltaX; } //求函数Function从a-b的积分，步长为lenth double integralFunction(double a, double b,double lenth) { double i,sum=0; for(i=a;i<=b;i+=lenth) { sum+=Function(i)*lenth; } return sum; } //牛顿迭代求解法求函数Function初值为number的解 double NewtonFunction(double number) { double x=1; int i; for(i=0;i<1000;i++) { x=x-(x*x+log(x))/Rate(x); } return x; } void main() { double a,b,lenth; cout<<"输入积分下限a："; cin>>a; cout<<"输入积分上限b:"; cin>>b; cout<<"输入步长lenth:"; cin>>lenth; cout<<"函数Function从a-b的积分"<<integralFunction(a,b,lenth)<<endl; cout<<endl; double number; cout<<"牛顿迭代求解法求函数Function的解的初值为："; cin>>number; cout<<"牛顿迭代求解法求函数Function初值为"<<number<<"的解为"<<NewtonFunction(number)<<endl; /* for(double i = 0.1; i <= 1; i += 0.1) { cout << i << '\t'; cout << Function(i) << '\t'; cout << Rate(i) << '\n'; } */ }