- Research Article
3
- 10.1016/s0022-4049(98)00130-3
Linear constant coefficient differential (or difference) equations
- Mar 01, 2000
- Journal of Pure and Applied Algebra
- Vakhtang Lomadze
Linear constant coefficient differential (or difference) equations
The underlying structure inherent in the classical method of undetermined coefficients, which is used to obtain particular solutions to linear constant coefficient (LCC) difference or differential equations, is investigated. A system of equations of the form B=M/sup -1/ A is obtained, where B and A are vectors whose elements are the coefficients of the terms in the expressions for the input and solutions, respectively, to the LCC equations. The structure of M that arises for both LCC difference and differential equations, as well as moving-average (FIR) systems, are investigated. It is shown that M is always a lower triangular matrix of order (r-1)*(r+1), where r is the degree of the expressions for the input and solutions. Furthermore, M is characterized by r+1 unique elements, each one defining the diagonal and off-diagonal elements, and is a member of an infinite set of matrices, all of order r+1, which form a group. M can be obtained whenever A and B are given. As a result, if one desires an FIR filter whose output is some linear operation, then the computation of M from A and B imposes a set of necessary and sufficient conditions.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Linear constant coefficient differential (or difference) equations
Linear constant coefficient differential (or difference) equations
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The method of undetermined coefficients is used to solve constant coefficient nonhomogeneous differential equations whose forcing function is itself the solution of a homogeneous constant coefficient differential equation. In this paper, we show that the classical methods for tackling constant coefficient equations, including the method of undetermined coefficients, generalize to much wider class linear differential equations which, for example, include Cauchy-Euler type equations. This general method includes an explicit construction of the fundamental solution sets of such equations. We also briefly consider where this method can be applied by producing the most general second and third order differential equations that are polynomial in a first order differential operator. In addition, we provide a number of constant coefficient, Cauchy-Euler, and novel examples.
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Having developed classes that underpin linear algebra operations in an earlier chapter, we now demonstrate how to construct object-oriented libraries for scientific computing applications that utilise the functionality of these classes. We use the specific example of developing a library that uses the finite difference method to solve boundary value, second order, constant coefficient differential equations. We begin by considering ordinary differential equations. We state the theory that underpins the finite difference method for these equations, and then describe the classes that we will develop to allow this theory to be applied. We then briefly discuss how to develop a library for the solution of Poisson’s equation, an elliptic partial differential equation, in two spatial dimensions.
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* Preface * Background Material * Computational Algebraic Analysis for Systems of Linear Constant Coefficients Differential Equations * The Cauchy-Fueter Systems and its Variations * Special First Order Systems in Clifford Analysis * Some First Order Linear Operators in Physics * Open Problems and Avenues for Further Research * References * Index
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