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Program to find f(x) by Lagrange's interpolation method.

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Program to find f(x) by Lagrange's interpolation method.


CODE

👇

  1. #include<stdio.h>
  2. #include<conio.h>

  4. void main()
  5. {
  6.     float x[10], y[10], temp = 1, f[10], sum, p;
  7.     int i, n, j, k = 0, c;

  9.     printf("How many record you will enter : ");
  10.     scanf("%d", &n);
  11.     for (i = 0; i < n; i++)
  12.     {
  13.         printf("\n\nenter the value of x%d: ", i);
  14.         scanf("%f", &x[i]);

  16.         printf("\n\nEnter the value of f(x%d): ", i);
  17.         scanf("%f", &y[i]);
  18.     }

  20.     printf("\n\nEnter X for finding f(x): ");
  21.     scanf("%f", &p);

  23.     for (i = 0; i < n; i++)
  24.     {
  25.         temp = 1;
  26.         k = i;
  27.         for (j = 0; j < n; j++)
  28.         {
  29.             if (k == j)
  30.             {
  31.                 continue;
  32.             }
  33.             else
  34.             {
  35.                 temp = temp * ((p - x[j]) / (x[k] - x[j]));
  36.             }
  37.         }
  38.         f[i] = y[i] * temp;
  39.     }

  41.     for (i = 0; i < n; i++)
  42.     {
  43.         sum = sum + f[i];
  44.     }

  46.     printf("\n\nf(%.1f) = %f ", p, sum);
  47. }

👉Execute👈
//OUTPUT
/*

*/