function logLikt = logLik(s2eps,s2,l,ns,xs,fs,type)     
if nargin == 6
    type = 'gauss';
end
F = ones(ns,1);
Rt = correlationfunc(l,xs,xs,type);
Sigmat = s2*Rt + s2eps*eye(ns);
[TSigmat,p] = chol(Sigmat);
xt = TSigmat'\fs;
Mt = TSigmat'\F;
bt = (Mt'*Mt)\(Mt'*xt);  % b = inv(F'*S^(-1)*F)*F'*S^(-1)*fs;
zt = xt - Mt * bt;
zzt = zt'*zt; % zz = (fs-F*b)'*Sigma^(-1)*(fs-F*b);
logLikt =  - sum(log(abs(diag(TSigmat)))) - 0.5*ns*log(2*pi) - 0.5*zzt;