The LinearOperators[dAlembertianSolver] function returns a d'Alembertian solution of the given inhomogeneous linear functional equation with a d'Alembertian right hand side if such a solution exists. Otherwise, it returns FAIL.

An Ore operator is a structure that consists of the keyword OrePoly with a sequence of coefficients starting with the one of degree zero. The coefficients must be rational functions in x. For example, in the differential case with the differential operator D, OrePoly(2/x, x, x+1, 1) represents the operator .

The right hand side b must be a d'Alembertian term. The main property of a d'Alembertian term is that it is annihilated by a linear operator that can be written as a composition of operators of the first degree. The set of d'Alembertian terms has a ring structure. The package recognizes some basic d'Alembertian terms and their ring-operation closure terms. The result of the substitution of a rational term for the independent variable in the d'Alembertian term is also a d'Alembertian term.

The routine returns an error message if the right hand side is not d'Alembertian.

Abramov, S. A., and Zima, E. V. "D'Alembertian Solutions of Inhomogeneous Equations (differential, difference, and some other)." In Proceedings ISSAC '96, pp. 232-240. Edited by Y. N. Lakshman. New York: ACM Press, 1996.