分段线性插值.cpp

牛顿 拉格朗日 分段线性

#include <iostream.h>
const int N=4;
void main()
{
	double x[N],y[N];
	int i;
	double X;
	double s=0;
    cout<<"Input X[N]:";
	for(i=0;i<N;i++)
	{
		cin>>x[i];
	}
	cout<<"Input Y[N]:";
	for(i=0;i<N;i++)
	{
		cin>>y[i];
	}
	cout<<"x=";
	cin>>X;
	for(i=0;i<N;i++)
	{
		if(X>=x[i]&&X<=x[i+1])
		{
			s=((x[i+1]-X)/(x[i+1]-x[i]))*y[i]+((X-x[i])/(x[i+1]-x[i]))*y[i+1];
		}
		else continue;
	}
	cout<<s<<endl;
}