function [b,a] = cas2dir(b0,B,A);
% CASCADE-to-DIRECT form conversion
% ---------------------------------
% [b,a] = cas2dir(b0,B,A)
%  b = numerator polynomial coefficients of DIRECT form
%  a = denominator polynomial coefficients of DIRECT form
% b0 = gain coefficient
%  B = K by 3 matrix of real coefficients containing bk's
%  A = K by 3 matrix of real coefficients containing ak's
%
[K,L] = size(B);
b = [1];
a = [1];
for i=1:1:K
	b=conv(b,B(i,:));
	a=conv(a,A(i,:));
end
b = b*b0;