simpson.cpp

来自「使用C++编写的经典数值计算算法,包括NEWTON迭带法,SIMPSON,二分法」· C++ 代码 · 共 34 行

//simpson
#include<iostream.h>
#include<math.h>
double f(double x)
{
	double b;
    b=sin(x*x);
	return b;
}
void main(void)
{
	float a;
	cout<<"输入下限a:";
	cin>>a;
	float b;
	cout<<"输入上限b:";
	cin>>b;
	int n;
	cout<<"输入n:";
	cin>>n;
	double h=(b-a)/(2*n);
	double s0=f(a)+f(b);
	double s1=0;
	double s2=0;
	int k;
	for(k=1;k<=2*n-1;k++)
	{
		double x=a+k*h;
		if(k%2==0) s2=s2+f(x);
		else s1=s1+f(x);
	}
	double sum=h*(s0+4*s1+2*s2)/3;
	cout<<"积分的值为："<<sum;
}