Convert filter poles and zeros to second-order sections.
- z = column-vector containing the filter zeros
- p = column-vector containing the filter poles
- k = overall filter gain factor If not given the gain is assumed to be 1.
- sos = matrix of series second-order sections, one per row:sos = [B1.' A1.'; ...; BN.' AN.']
.' = [b0 b1 b2] andA1
.' = [1 a1 a2]for section 1, etc. The b0 entry must be nonzero for each section. See
filterfor documentation of the second-order direct-form filter coefficients Bi and %Ai, i=1:N.
- g is the overall gain factor that effectively scales any one of the Bi vectors.
If called with only one output argument, the overall filter gain is applied to the first second-order section in the matrix sos.
EXAMPLE:[z, p, k] = tf2zp ([1 0 0 0 0 1], [1 0 0 0 0 .9]); [sos, g] = zp2sos (z, p, k) 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.