I am getting confused from the implementation regarding matlab function filter([b0,b1,b2],[a1,a2],x)
and other function similar as freqz
. I do not understand which sign I must put in a
coefficients, since there is two different way of writing the transfer function for the same second order filter as you see on the these pic below
when for example the besself
function generate the coefficients, does it generate them as I write them $H(z)$ or I must write $1-a_0z^{-1}-a_2z^{-2}$?