function uu = normcdf(xx, mu, sigma)
%NORMCDF Gaussian CDF without using the stats toolbox
%
%     uu = normcdf(xx, mu, sigma)

% Iain Murray, July 2012

if ~exist('mu', 'var')
    mu = 0;
end
if ~exist('sigma', 'var')
    sigma = 1;
end

uu = 0.5*erf((xx-mu)./(sigma*sqrt(2))) + 0.5;