Function File: [sos, g] = zp2sos (z, p)

Function File: [sos, g] = zp2sos (z, p, g)

Convert filter poles and zeros to second-order sections.

INPUTS:

• z = column-vector containing the filter zeros
  
• p = column-vector containing the filter poles
  
• g = overall filter gain factor If not given the gain is assumed to be 1.

RETURNED:

• sos = matrix of series second-order sections, one per row:
  sos = [B1.' A1.'; ...; BN.' AN.'], where
  B1.'==[b0 b1 b2] and A1.'==[1 a1 a2] for section 1, etc.
  b0 must be nonzero for each section.
  See filter() for documentation of the second-order direct-form filter coefficients Bi and %Ai, i=1:N.
• Bscale is an overall gain factor that effectively scales any one of the Bi vectors.

EXAMPLE:

            [z,p,g] = tf2zp([1 0 0 0 0 1],[1 0 0 0 0 .9]);
            [sos,g] = zp2sos(z,p,g)
          
          sos =
             1.0000    0.6180    1.0000    1.0000    0.6051    0.9587
             1.0000   -1.6180    1.0000    1.0000   -1.5843    0.9587
             1.0000    1.0000         0    1.0000    0.9791         0
          
          g =
              1

See also: sos2pz sos2tf tf2sos zp2tf tf2zp