hi, im little new using matlab and these is my first post ^^

I have use the function impz to do it and i need to compare with the
response using filter, but im no relly sure how to do it.

with impz 

N = 40;
num = [0.9 -0.45 0.35 0.002];
den = [1 0.71 -0.46 -0.62];
y = impz(num,den,N);

what i tryed 

N = 0:40;
num = [0.9 -0.45 0.35 0.002];
den = [1 0.71 -0.46 -0.62];

y = filter(num,den,N);  

no really sure is these is rigth

any help is welcome

advanced thanks