How can i get a transfer function from coefficient vector of size 1xn+1?

Hi

It was requested that from a input coefficient vector of size 1 x n+1, where n is the order of the polynomial, get a rlocus plot and compute the Routh Hurwitz. The Routh stabilty creterion is already done, but the problem with my solution for the first item is that it just work if there is a 'K' controller in the input vector, eg: [2 5 9 6+K 8K], but it wont work for [2 5 9 6 8]. However, i just want to get a transfer function ([num],[dem]) from a imput vector like [ a b c d ] that comes from aS^3+bS^2+cS+d .

Thanks.

[Raj]

Sorry but your question is not clear at all. Can you rephrase what exactly are you looking for?

[Synchro_mdn]

The characteristic equation : HG+1 = 1+ 2/(s²+3s+4) =0. Then (s²+3s+4) + 2 = s²+3s+6 =0. The input vector will be [ 1 3 6]. That structure is just fine for Routh. But I need to get the original tf (2/(s²+3s+4)), from the input vector [ 1 3 6], it could be any coefficient vector.

[David Wilson]

I'm not sure you can unless you know the gain independently.

For example and will both give you the same polynomial, .