Parallel SOS to Transfer Function: psos2tf.mFigure J.10 lists a matlab function for computing the direct-form transfer-function polynomials from parallel second-order section coefficients. This is in contrast to the existing function sos2tf which converts series second-order sections to transfer-function form.
function [B,A] = psos2tf(sos,g) if nargin<2, g=1; end [nsecs,tmp] = size(sos); if nsecs<1, B=; A=; return; end Bs = sos(:,1:3); As = sos(:,4:6); B = Bs(1,:); A = As(1,:); for i=2:nsecs B = conv(B,As(i,:)) + conv(A,Bs(i,:)); A = conv(A,As(i,:)); end
Group Delay Computation: grpdelay.m
Partial Fraction Expansion: residued.m