文档介绍：#include<cstring>
#include<>
#include<>
#include<iostream>
#include<>
#include<>
usin>>y0>>x1>>y1>>x2>>y2;
y01=(y0-y1)/(x0-x1);y12=(y1-y2)/(x1-x2);y012=(y01-y12)/(x0-x2);
ym=y0+(x-x0)*y01+(x-x0)*(x-x1)*y012;
cout<<"please input xm:"<<endl;
cin>>xm;
cout<<"ym="<< y0+(xm-x0)*y01+(xm-x0)*(xm-x1)*y012<<endl;
}
void sub44()
{
int n,i,j;
double xm,ym=0;
double x[200],y[200], l[200];
cout << "input n=”;
cin >> n;
cout << endl;
cout << "input xm=";
cin >> xm;
cout << endl;
for(i=0;i<=n;i++)
{
cout << "x[" << i << "]=";
cin >> x[i];
cout << endl;
}
for(i=0;i<=n;i++)
{
cout << "y[" << i << "]=";
cin >> y[i];
cout << endl;
}
for(i=0;i<=n;i++)
{
double b=1,c=1;
for(j=0;j<=n;j++)
{
if(i!=j){b=b*(xm-x[j]);}
}
for(j=0;j<=n;j++)
{
if(i!=j){c=c*(x[i]-x[j]);}
}
l[i]=b/c;
}
for(i=0;i<=n;i++)
{
ym=ym+y[i]*l[i];
}
cout << ym<<endl;
}
void sub55()
{
int i,n;
double xm,ym;
cout << "input xm=”;
cin >> xm;
cout << endl;
cout << ”你现在拥有几个点的坐标？至少得有2个点”;
cin >> n;
cout << endl;
cout << ”那么你现在一一输入这些坐标\n”;
double x[200],y[200];
for(i=0;i<n;i++)
{
cout << "x[" << i << "]=";
cin >> x[i];
cout << endl;
}
for(i=0;i<n;i++)
{
cout << "y[" << i << "]=";
cin >> y[i];
cout << endl;
}
for (i = 0; i<n; i++)
{
if (x[i] <= xm && xm<=x[i+1])
ym=(y[i]*((xm-x[i+1])/(x[i]-x[i+1]))+y[i+1]*((xm-x[i])/(x[i+1]-x[i])));