LFJP'LS
↓
程序如下：
#include <iostream>
#include <conio.h>
#include <malloc.h>
float lagrange(float *x,float *y,float xx,int n) /*拉格朗日插值算法*/ {
int i,j;
float *a,yy=0.0; /*a作为临时变量，记录拉格朗日插值多项式*/ 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;
}
int main()
{
int i;
int n;
float x[20],y[20],xx,yy;
printf("Input n:");
scanf("%d",&n);
if(n>=20)
{
printf("Error!The value of n must in (0,20)."); getch();return 1; }
if(n<=0)
{
printf("Error! The value of n must in (0,20)."); getch(); return 1; }
for(i=0;i<=n-1;i++)
{