lagelangri.txt

拉格朗日插值法VC++源程序 牛顿插值源程序

#include<stdio.h>
float Lagrange(float x[],float y[],float xx,int n)
{
	int i,j;
	float*a,yy=0;
	a=new float[n];
	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];
	}
	delete 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=0.5635,yy;
	yy=Lagrange(x,y,xx,4);
	printf("x=%f,y=%f\n",xx,yy);
}