\psaxes{->}(0,0)(-2,0)(2,4) \psset{linewidth=2\pslinewidth} \psplot[linecolor=gray]{-2}{2}{x 2 exp} \psplot{-2}{2}{2 x 2 div sub} \psset{PointSymbol=o} \pstInterFF{2 x 2 div sub}{x 2 exp}{1}{M_1} \pstInterFF{2 x 2 div sub}{x 2 exp}{-2}{M_0}