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sos2zp() - Signal Processing

```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 byH(z)=∏k=1LHk(z)=∏k=1Lb0k+b1kz−1+b2kz−21+a1kz−1+a2kz−2.sos is an L-by-6 matrix
that contains the coefficients of each second-order section in its
rows.sos=[b01b11b211a11a21b02b12b221a12a22⋮⋮⋮⋮⋮⋮b0Lb1Lb2L1a1La2L].Column vectors z and p contain
the zeros and poles of the transfer function H(z).H(z)=k(z−z1)(z−z2)⋯(z−zn)(p−p1)(p−p2)⋯(p−pm)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.H(z)=g∏k=1LHk(z).```

Syntax

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

Example

```Zeros, Poles, and Gain of a SystemOpen This Example
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 =

-1.0000
1.0000
-9.8990
-0.1010

k =

-2```