lgr.c

拉氏算法以及最小平方

double lgr(double *x,double *y,double u,int n)
{
	double v,l1,l2;
	int i,j;
	double tx[9],ty[9];

	memcpy(tx,x,sizeof(double)*9);
	memcpy(ty,y,sizeof(double)*9);

	v=0;
	for(i=0;i<=n;i++)
	{
		l1=l2=1;
		for(j=0;j<=n;j++)
		{
			if(j!=i)
			{
				l1*=(u-x[j]);
				l2*=(x[i]-x[j]);
			}
		}
		v+=y[i]*(l1/l2);
	}
	return v;
}