拉

#include<iostream>#include<conio.h>using namespace std;float Lagrange(float *x,float *y,float xx,int n){ int i,j;  float *a, yy=0.0;  a=(float *)malloc(n*sizeof(float));  for(i=0;i<=n-1;i++){ a[i]=y[i];  for(j=0;j<=n-1;j++)  if(j!=i)a[i]*=(xx-x[j])/(x[i]-x[j]);  yy+=a[i];}free(a);return yy;}void main(){float x[4]={0.56160,0.56280,0.56401,0.56521}; float y[4]={0.82741,0.82659,0.82577,0.82495}; float xx=0.563500,yy; float Lagrange(float *,float *,float,int); yy=Lagrange(x,y,xx,4); system("cls"); cout<<"表5-10为"<<endl; cout<<"  x[i]="<<"0.56160   0.56280   0.56401   0.56521"<<endl; cout<<"  y[i]="<<"0.82741   0.82659   0.82577   0.82495"<<endl; cout<<"计算结果为"<<endl; cout<<"  x="<<xx<<"   "<<"y="<<yy<<endl; getch();}

拉格朗日多项式