twoway (function y = 1 + 1*x, range(0 5)), ///
ylabel("") xlabel("") xsize(4) ysize(4) ///
title(Linear function) name(figure9a, replace)
twoway (function y = exp(x) / (1 + exp(x)), range(-5 5)), ///
ylabel("") xlabel("") xsize(4) ysize(4) ///
title(Logistic function) name(figure9b, replace)
graph combine figure9a figure9b, col(2) xsize(8) ysize(4) ///
altshrink name(figure9, replace)
