Intanto ce l’ho fatta con questa:
`\begin{pspicture}(-2,-2)(2,2)
\psset{algebraic}
\begin{psclip}{\pspolygon(-3,-3)(-3,3)(3,3)(3,-3)}
\psaxes[ticks=none, linewidth=.3pt, xunit=2](0,0)(-4,-4)(4,4)
\psplot[linecolor=red]{0}{\la2}{sqrt(x*(x-1)*(x-\la2))}
\psplot[linecolor=red]{1}{3}{sqrt(x*(x-1)*(x-\la2))}
\psplot[linecolor=red]{0}{\la2}{-sqrt(x*(x-1)*(x-\la2))}
\psplot[linecolor=red]{1}{3}{-sqrt(x*(x-1)*(x-\la2))}
\psplot[linewidth=.4pt]{-4}{4}{.7*x+1}
%
\pnode(-1.97509, -0.382565){A}
\pnode(-0.288693, 0.797915){A*B}
\pnode(1.75379, 2.22765){B}
\pnode(-1.7, 1.17346){O}
\psdot(A)\uput[0](A){$A$}
\psdot[linecolor=blue](A*B)\uput[0](A*B){$A*B$}
\psdot(B)\uput[0](B){$B$}
\psdot(O)\uput[0](O){$O$}
\psplot[linewidth=.4pt]{-4}{4}{0.721095 – 0.266095*x}
\pnode(1.0595, 0.439168){A+B}
\psdot(A+B)\uput[0](A+B){$A+B$}
\end{psclip}
\end{pspicture}`
Suggerimenti per qualche miglioria?