[code]class List{
   node head; //it does not hold meaningful data
};

void List::List(): head(&head) //circular
{}

void List::Add(double data){
   node *lower_bound = &head;
   while( lower_bound->next != &head and lower_bound->next->data < data )
      lower_bound = lower_bound->next;
   //here it holds that `lower_bound->next->data > data'
   //or that we are at the end of the list
   lower_bound->next = new node(data, lower_bound->next);
}[/code]