cacul.zip_求积分

#include<iostream> #include<math.h> using namespace std; double f(double x); //被积函数 double jifen_fuhua_simpson(double(*f)(double),double a,double b,int n); //辛普森求积分 double jifen_fuhua_tixing(double(*f)(double),double a,double b,int n); //梯形求积分 int main() { cout<<jifen_fuhua_tixing(f,0,3.1415926,100)<<" "; cout<<jifen_fuhua_simpson(f,0,3.1415926,11); system("pause"); return 1; } double f(double x) { return sin(x); } double jifen_fuhua_simpson(double(*f)(double),double a,double b,int n) { double step=(b-a)/n; double sum=0; for(int i=0;i<=n-1;i++) sum+=4*f(a+(i+0.5)*step); for(int i=1;i<=n-1;i++) sum+=2*f(a+i*step); return step*(f(a)+f(b)+sum)/6.0; } double jifen_fuhua_tixing(double(*f)(double),double a,double b,int n) { double step=(b-a)/n; double sum=0; for(int i=1;i<=n-1;i++) sum+=f(a+i*step); return step*(sum*2+f(a)+f(b))/2.0; }