Foxmaths! 2.0

January 8, 2008

Generating Functions

Filed under: Maths — Tags: , , , — Fox @ 9:36 pm

Generating Functions are a neat tool in the study of recursive sequences.

A generating function is a clothesline on which we hang up a sequence of numbers for display.
— Herbert Wilf, Generatingfunctionology (1994)

The idea is that, given a sequence of numbers a_0, a_1, a_2, ..., we want to examine functions of the following form.

f(x) = a_0 + a_1 x + a_2 x^2 + ... = \sum_{n = 0}^\infty a_n x^n

This is the so called ‘ordinary’ generating function. By examining properties of f(x), we can derive information about the formula for that sequence of numbers.
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