| Signal Processing Toolbox | Help Desk |
sos2tf
Second-order section to transfer function conversion.
[b,a] = sos2tf(sos)
sos2tf converts a second-order section representation of a given system to an equivalent transfer function representation.
[b,a] = sos2tf(sos)
returns the numerator coefficients b and denominator coefficients a of the transfer function that describes a discrete-time system given by sos in second-order section form. The second-order section format of H(z) is given by
where L is the number of rows of sos. sos is an L-by-6 matrix which contains the coefficients of each second-order section stored in its rows:
Row vectors b and a contain the numerator and denominator coefficients of H(z) stored in descending powers of z:
sos2tf uses the conv function to multiply all of the numerator and denominator second-order polynomials together.
Compute the transfer function representation of a simple second-order section form system:
sos = [1 1 1 1 0 -1; -2 3 1 1 10 1];
[b,a] = sos2tf(sos)
b =
-2 1 2 4 1
a =
1 10 0 -10 -1