need help with IIR filter

[theChris]

this is for a school project. I need to make an AA filter for resampling a file. i've done this with a FIR filter and using Matlab's default, and using an averaging filter, but i would like to add a IIR filter to the mix as well. i'm not sure my results were very good.

i made 2 matrixs with 11 elements each, for my coefficients.

then i made 2 matrixs 10 elements long to hold x(n) to x(n-9).

maybe i left off a term, i think there was supposed to be a x(n-10) as well.

the algorithm shifts in a value of x, then runs the equation summing the elements of a*x and b*y then placing then shifting the result into the y matrix.

am i anywhere near correct on this?

in anycase i don't really need the IIR to be correct, it's mainly to impress the teacher with our project. this isn't a DSP class, just communications. but i would like to get it working.