It seems that normcdf is not defined for sym objects. You can try to express normcdf for syms in a more elementary way, like this:
normcdfsym = @(x, mu, sigma)(1/2 - erf((2^(1/2)*(mu - x))/(2*(sigma^2)^(1/2)))/2)
With this your formular would look like this:
f2 = -(-N_M*log(eta+lembda*(1-normcdfsym(log(M_minw),mu,sigma)))+N_M*log(lembda)+Nu_M*log(1-normcdfsym(log(M_minw),mu,sigma))+Nu_M*log(eta)-Ne_M*log((sqrt(2*pi)*sigma))-sum(log(M(n,2)))-sum((log(M(n,2))-ones(n,1)*mu).^2/(2*sigma^2))-lembda*(1-normcdfsym(log(M_minw),mu,sigma))*sum(M(n(end)+1:end,1)));
However there are still some undefined variables, like N_M or M.
