function y = genar1(alpha, rho, sig2, T, y0, repeat);

% input:  alpha - constatnt
%         rho - coefficient on y(t-1) term
%         sig2 - variance on error term for your process
%         T - number of observations in the series
%         y0 - first value in the generated sequence
%         repeat - how many series of length T to generate
% output: y - the simulated ar(1) process  

if (rho > 1); 
    error('You asked for an explosive AR(1) series!'); 
end 

%initialize the y vector and fill it with 9999 so we know when we've
%replaced the original values.

y = 9999*ones(T,repeat);
y(1,1:repeat) = y0;
for r = 1:1:repeat
    for t = 2:1:T;
        y(t,r) = alpha + rho*y(t-1,r) + normrnd(0,sqrt(sig2));
    end
end