#include <stdio.h>
#include <stdlib.h>
#include <assert.h>


double * aitken(double * x, int n) {

  double * y = NULL;
  int j = 0;

  y = malloc ((n-2)*sizeof(double));
  assert (y != NULL);

  for (j = 0; j < n-2; j++) {

    y[j]= x[j] - ((x[j+1]-x[j])*(x[j+1]-x[j]))/(x[j+2]-2*x[j+1]+x[j]);

  }

  return y;
}

double * scanVector( int dim){

  int j = 0;
  double * vector = NULL;
  assert (dim > 0);


  vector= malloc(dim*sizeof(double));
  assert(vector != NULL);

  for (j = 0 ; j < dim; j++) {
    printf("Geben Sie die %dte Stelle der Folge ein:",j);
    scanf("%lf",&vector[j]);


  }
  return vector;
}


double * printVector(double*vector, int dim) {
  int j = 0;
  assert (dim > 0);
  assert (vector != NULL);
  for (j = 0; j< dim-2; j++) {

    printf("y[%f]\n",vector[j]);

  }

}

int main () {


  int n = 0;
  double *x = NULL;
  double *y = NULL;

  printf("Geben Sie eine Anzahl der Folgenglieder n (n>3) ein:");
  scanf("%d",&n);

  assert (n > 3);

  x=scanVector(n);


y=aitken(x,n);

 printVector(y,n);

 free (x);
 free (y);
}