직교다항식(orthogonal polynomials)
Difference Equations, Continued Fractions, and Orthogonal Polynomials (Walk Into a Bar) http://math.illinoisstate.edu/schebol/algebra-seminar-files/ortho.pdf
Why is electrostatics in the complex plane interesting from a mathematical point of view?
http://www.maths.leeds.ac.uk/~kisilv/courses/sp-funct.pdf