# Difference Equation Coefficients

1. Oct 13, 2012

1. The problem statement, all variables and given/known data

Work out the correct coefficient arrays for these equations:

y(n)=y(n-1)+$\frac{1}{5}$(x(n)-x(n-5))

y(n) = 0.82y(n -1) + .28x(n)

2. Relevant equations

$\sum a(r)y(n+1-r)$=$\sum b(k)y(n+1-k)$ where a(1) = 1


3. The attempt at a solution
Ok for the second equation the coefficients are clearly 0.82 and 0.28, now if I were to put that in an array for matlab would it be [0.82 0 0 0 0] and [0.28 0.28 0.28 0.28 0.28]?

For the first equation I have no idea how to go about finding the coefficients.

Cheers for any help.

2. Oct 13, 2012

### HallsofIvy

Staff Emeritus
I think it would be helpful to you to start by determining exactly what the "variables" in this problem are. That is, what will the coefficient matrix be multiplying and what result should that matrix multiplication give?