拉格朗日插值.txt

拉格朗日插值

#include<stdio.h>
#define ZD 20
main()
{
  int k,n,j;
  float h[ZD],f[ZD];
  float y,l,x;
  printf("Input n:");
  scanf("%d",&n);
  printf("Input n+1 ge shjd:\n");
  for(k=0;k<=n;k++)
  {
    scanf("%f,%f",&h[k],&f[k]);
  }
  xun:
    y=0.0;
    printf("Input x:");
    scanf("%f",&x);
    for(k=0;k<=n;k++)
    {
      l=1.0;
      for(j=0;j<=n;j++)
      {
		if(j!=k)
		{
          l=l*(x-h[j])/(h[k]-h[j]);
		}
		else  continue;
      } 
      y=y+l*f[k];
    }
    printf("y=%f\n",y);
  goto xun;
}