cz.cpp

二次插值的计算方法

#include <iostream.h>

class cz
{
private:
	long double a,b,c;
	long double f1,f2,f3;
	long double x1,x2,x3;
	long double xx;
	long double k1,k2;
public:
	long double jzd()   // 极值点
	{   
		k1 = (f3-f1)/(x3-x1);
		k2 = (((f2-f1)/(x2-x1)-k1)/(x2-x3));
		xx = 0.5*(x1+x2-(k1/k2));
		return (xx);

	}
	void input2(long double *p, long double *m)
	{
         x1=*p;x2=*(p+1);x3=*(p+2);
		 f1=*m;f2=*(m+1);f3=*(m+2);

	}

};

void input(long double *p,long double *m)
{
	int i;
	
	for(i=1;i<4;i++)
	{	cout<<"输入第"<<i<<"个点值:     ";
	    cin>>*(p-1);
	    cout<<"输入第"<<i<<"个点的函数值:";
		cin>>*(m-1);
		cout<<endl;
	}
}
void main()
{
	long double a[3];
	long double b[3];
	cz eg;
	input(a,b);
	eg.input2(a,b);
	cout<<"极值点为"<<eg.jzd()<<endl;
}