## Regular Singular Point

Consider a second-order Ordinary Differential Equation

If and remain Finite at , then is called an Ordinary Point. If either or diverges as , then is called a singular point. If either or diverges as but and remain Finite as , then is called a regular singular point (or Nonessential Singularity).

Arfken, G. Singular Points.'' §8.4 in Mathematical Methods for Physicists, 3rd ed. Orlando, FL: Academic Press, pp. 451-453 and 461-463, 1985.