求个c++编程 用蒙特卡洛法算积分 跪求一大神帮忙 跪求

Answer 1

随便写了下，也没怎么检查，大致算法就是这样。你可以参考参考。

#include <iostream>
#include <ctime>
#include <cmath>
using namespace std;

const double PI = acos(-1);
const int MAXR = 999;
double interval[MAXR+10];
int n;
const double a = 0;
const double b = PI/2;

double func(double x)
{
return 4/(3*sqrt(1-sin(PI/12)*sin(PI/12)*sin(x)*sin(x)));
}

void genRandomInterval(double a,double b)
{
srand( (unsigned)time( NULL ) );
n=rand()%MAXR;
if(n%2==0)n++;
interval[0]=a;
interval[n+1]=b;
for(int i=1;i<=n;i++)
interval[i]=a+(b-a)*(i+0.5)/n;
}

double integral()
{
double ret=0;
genRandomInterval(a,b);
for(int i=1;i<=n;i++)
ret+=func(interval[i])*(interval[i+1]-interval[i-1]);
return ret;
}

int main()
{
int m;
cout<<"Please input the experiment time: ";
cin>>m;
cout<<"Processing "<<m<<" experiments and output the average value."<<endl;
double ans=0;
for(int i=0;i<m;i++)
ans+=integral();
ans/=m;
cout<<"The average value is "<<ans<<endl;
system("pause");
}