I'm trying to construct a higher order IIR from a biquad cascade, I know this is generally frowned upon, but it's necessary as the coefficients will be embedded into a larger formula used in a FDTD boundary condition.
According to this answer, I simply need to multiply the biquad transfer functions together, however I'm not sure how to do that. Is it simply a case of multiplying each numerator polynomial into a higher order one, and then doing the same for the denominator?