Frequency response function In matlab

Can someone help me with this matlab frequency response problem.

This is what I have so far, but code doesnt work.

function [H] = freqresp(b, a, w)

a(1) = 1;

numer(0) = 0;

denom(1) = 0;

for k=1:length(b)

numer(k) = numer(k-1) + b(k) * exp(i*w*k);
end 

for m=2:length(a)

denom(m) = denom(m-1) + a(m)*exp(i*w*k);

end

H = numer/denom;

Answer 1

[Walter Roberson]

You have

numer(0) = 0;

In MATLAB, indexing can never start from 0. You need

numer(1) = 0;

for k=1:length(b)
  numer(k+1) = numer(k) + b(k) * exp(i*w*k);
end 

for m=1:length(a)
  denom(m+1) = denom(m) + a(k)*exp(i*w*k);
end

But after that you have a problem. You could try

H = numer ./ denom

but if length(a) and length(b) are not the same, you have a problem.