//scanVector
double* scanVector(int length){
  int i = 0;
  double* vector = NULL;
  assert(length > 0);

  vector = malloc(length*sizeof(double));
  for(i=0; i<length; i++){
    printf("vector[%d]: \n", i);
    scanf("%lf", &vector[i]);
  }
  return vector;
}