NEWTON BACKWARD INTERPOLATION USING C PROGRAM

#include<stdio.h>
int main()
{
int n;
printf("enter size");
scanf("%d",&n);
float ax[n];
float ay[n];
int i,j;
for(i=0;i<n;i++)
{
printf("enter ax[%d]\n",i);
scanf("%f",&ax[i]);
printf("enter ay[%d]\n",i);
scanf("%f",&ay[i]);
}
float d;
printf("enter intermediate value of x");
scanf("%f",&d);
float y=1,p;
p=(d-ax[n-1])/(ax[1]-ax[0]);
float a[n][n];
for(i=0;i<n;i++)
{
a[i][0]=ay[i];
}
for(i=1;i<n;i++)
{
for(j=0;j<n;j++)
{
a[j][i]=a[j+1][i-1]-a[j][i-1];
}
}
float g=ay[n-1];
for(i=1;i<n;i++)
{
y=(y*(p+i-1))/i;
g=g+(y*a[n-i-1][i]);
}
printf("value of y=%f ",g);
return 0;
}