Who is Alex's Father (Jake) from Portnoy's Complaint and what is their importance?

According to Alex's portrayal of him, his father is a somewhat less damaging and controlling influence than his mother, but from Alex's point of view has inflicted his share of emotional and psychological harm. Physically absent for much of Alex's life (he is described, at one point, as a stranger who came to stay every weekend) and suffering from chronic constipation (see "Chapters 1 and 2 Analysis"), he is seen by Alex as a failure as a father, a husband and a man. According to Alex, his father provided for his family's physical needs, but never provided anything else.