function G=extcdf(mu,sigma2,d,tmax);
% extcdf(mu,sig2,d,tmax) calculates the unconditional extinction time 
% cumulative distribution function from t=1 to t=tmax for mean and  
% variance parameters mu and sigma2 and log distance from the  
% quasi-extinction threshold d; modified from Lande and Orzack, 
% Proc. Nat. Acad. Sci. USA 85: 7418-7421 (1988), equation 11.
% REQUIRES THE FILE stdnormcdf.m
for t=1:tmax
    G(t)=stdnormcdf((-d-mu*t)/sqrt(sigma2*t)) + ...
        exp(-2*mu*d/sigma2)*stdnormcdf((-d+mu*t)/sqrt(sigma2*t));
end;