这是牛顿插值,拉格朗日暂时没写出来
#include "stdafx.h"
void main()
{
float x[3]={0.1,0.2,0.4};
\x05float y[3]={0.2,0.5,1.0};
\x05float b[3],l,z;
\x05printf("请输入x的值!\n");
\x05scanf("%f",&z);
\x05b[0]=y[0];
\x05b[1]=y[0]/(x[0]-x[1])+y[1]/(x[1]-x[0]);
\x05b[2]=y[0]/((x[0]-x[1])*(x[0]-x[2]))+y[1]/((x[1]-x[0])*(x[1]-x[2]))+y[2]/((x[2]-x[0])*(x[2]-x[1]));
l=b[0]+b[1]*(z-x[0])+b[2]*(z-x[0])*(z-x[1]);
\x05printf("%f\n",l);
}