*! version 1.0.0  18Jan93 Royston; STB-11 sg1.4
program define nllog3
	version 3.0
        if "`1'"=="?" {
                local depv "$S_E_depv"
                nllog4 ? "`2'"
                mac def S_2 "3-parameter logistic function, `depv'=b1/(1+exp(-b2*(`2'-b3)))"
                mac def S_1 "b1 b2 b3"
                exit
        }
        replace `1'=$b1/(1+exp(-$b2*(`2'-$b3)))
end