Generating Function(redirected from Generating functional)
generating function[′jen·ə‚rād·iŋ ‚fəŋk·shən]
A generating function of the sequence f0, f1,..., fn is the function
assuming that this power series converges for at least one nonzero value of t.
The sequence f0, f1,..., fn,… can be a sequence of numbers or of functions. In the latter case, the generating function depends not only on t but also on the arguments of the functions fn. For example, if fn = aqn, where a and q are constants, the generating function is
If the fn are Fibonacci numbers—that is, if f0 = 0, f1 = 1, fn+2 = fn+1 + fn—we have
If fn = Tn (x) are Chebyshev polynomials—that is, if T0(x) = 1
and Tn (x) = cos (n arc cos x)—then
Knowledge of the generating function of a sequence often makes it easier to study the properties of the sequence. Generating functions are used in probability theory, in the theory of functions, and in the theory of invariants in algebra. Methods involving generating functions were first applied by P. Laplace to solve certain problems in probability theory.
REFERENCESFeller, W. Vvedenie v teoriiu veroiatnostei i eeprilozheniia, 2nd ed., vols. 1–2. Moscow, 1967. (Translated from English.)
Natanson, I. P. Konstruktivnaia teoriia funktsii. Moscow-Leningrad, 1949.