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Convert digital filter second-order section parameters to zero-pole-gain form


[z,p,k] = sos2zp(sos)
[z,p,k] = sos2zp(sos,g)


sos2zp converts a second-order section representation of a given digital filter to an equivalent zero-pole-gain representation.

[z,p,k] = sos2zp(sos) returns the zeros z, poles p, and gain k of the system given by sos in second-order section form. The second-order section format of H(z) is given by


sos is an L-by-6 matrix that contains the coefficients of each second-order section in its rows.


Column vectors z and p contain the zeros and poles of the transfer function H(z).


where the orders n and m are determined by the matrix sos.

[z,p,k] = sos2zp(sos,g) returns the zeros z, poles p, and gain k of the system given by sos in second-order section form with gain g.



collapse all

Compute the zeros, poles, and gain of a simple system in second-order section form.

sos = [1  1  1  1  0 -1; -2  3  1  1  10  1];
[z,p,k] = sos2zp(sos)
z = 
  -0.5000 + 0.8660i
  -0.5000 - 0.8660i
   1.7808 + 0.0000i
  -0.2808 + 0.0000i

p = 


k = -2


sos2zp finds the poles and zeros of each second-order section by repeatedly calling tf2zp.

See Also

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Introduced before R2006a

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