> Pstricks plot perfectly y = f(x). But is there a way to plot x =
> f^{-1}(y) directly without use ImplicitPlot or by outside generation
> of the datas ?
>
interesting question... if there were a possibility to draw reflections
(more precisely: take some part of a pstricks-picture and reflect it
along the line y=x), then it would be easy...