Module 4 : Solving Linear Algebraic Equations
Section 9 : Appendix A: Behavior of Solutions of Linear Difference Equations
 
9 Appendix A: Behavior of Solutions of Linear Difference Equations
Consider difference equation of the form
MATH --------(178)

where MATH and $\QTR{bf}{B}$ is a $n\times n$ matrix. Starting from an initial condition $\QTR{bf}{z}^{(0)}$, we get a sequence of vectors MATH such that
MATH
for any $k.$ Equations of this type are frequently encountered in numerical analysis. We would like to analyze asymptotic behavior of equations of these type without solving them explicitly.

To begin with, let us consider scalar linear iteration scheme

MATH --------(179)
where $z^{(k)}\in R$ and $\beta $ is a real scalar. It can be seen that
MATH --------(180)
if and only if MATHTo generalize this notation to a multidimensional case, consider equation of type (178) where MATH Taking motivation from the scalar case, we propose a solution to equation (178) of type
MATH --------(181)

where $\lambda $ is a scalar and MATH is a vector. Substituting equation (181) in equation (178), we get

MATH --------(182)
--------(183)
Since we are interested in a non-trivial solution, the above equation can be reduced to
MATH --------(184)