To Construct the New Data Points Using Newton's Forward Method of Interpolation - C Data Structure

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Description

To Construct the New Data Points Using Newton's Forward Method of Interpolation

Demo Code

#include<stdio.h>

#define MAX 20/*from ww w.j  a va  2  s  . co  m*/

void main()
{
  float ax[MAX], ay[MAX], diff[MAX][5];
  float nr = 1.0, dr=1.0, x, p, h, yp;
  int terms = 10, i, j, k;
  printf("\nEnter the values of x upto 2 decimal points.\n");
  for (i=0; i<terms; i++) {
    printf("Enter the value of x%d: ", i+1);
    scanf("%f",&ax[i]);
  }
  printf("\nNow enter the values of y upto 4 decimal points.\n");
  for (i=0; i<terms; i++) {
    printf("Enter the value of y%d: ", i+1);
    scanf("%f", &ay[i]);
  }
  
  x = 20;
  h = ax[1] - ax[0];
  for (i = 0; i < terms-1; i++)
    diff[i][1] = ay[i+1] - ay[i];
  for (j=2; j<=4; j++)
    for(i=0; i<=terms-j; i++)
      diff[i][j] = diff[i+1][j-1] - diff[i][j-1];
  i=0;
  do {
    i++;
  } while (ax[i] < x);
  i--;
  p = (x - ax[i]) / h;
  yp = ay[i];
  for (k=1; k <= 4; k++)     {
    nr *= p - k + 1;
    dr *= k;
    yp += (nr/dr) * diff[i][k];
  }
  printf("\nFor x = %6.2f,    y = %6.4f",x,yp);
}

Result


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