function a=gtoa(gamma)
%GTOA	Step-up recursion
%----
%USAGE	a = gtoa(gamma) 
%
%	The direct-form filter coefficients
%		a=[1 a(1) ... a(p)]
%	are derived from the reflection coefficients gamma
%	using the step-up recursion.
%
%  see also ATOG, ATOR, GTOR, RTOA, RTOG
%
%---------------------------------------------------------------
% copyright 1996, by M.H. Hayes.  For use with the book 
% "Statistical Digital Signal Processing and Modeling"
% (John Wiley & Sons, 1996).
%---------------------------------------------------------------

a=1;
gamma=gamma(:);
p=length(gamma);
for j=2:p+1;
	a=[a;0] + gamma(j-1)*[0;conj(flipud(a))];
	end