[pstricks] courbe avec pstricks et un peu de pscustom

[Herbert Voss]

idrevetnom schrieb:

> Mais je ne vois pas les étiquettes v_0, v_1, v_2, que devrait donner le
> \uput{1ex}[90](!x,0){$v_i$}

Without \pscustom it is a lot easier:

\documentclass{article}
\usepackage{amsmath}
\usepackage{pstricks-add}

\begin{document}

\begin{center}
\psset{xunit=2cm,yunit=2cm,algebraic=true}
\begin{pspicture}[showgrid=true](-5,-5)(1,1)
  \psaxes{->}(0,0)(-5,-5)(1,1)[$x$,-90][$y$,180]%
  \rput(-2,-3){{$y=\dfrac{-2x+8}{~~2x-2}$}}%
  \psplot {-5}{0.10}{x }%
  \psplot[linecolor=red,linewidth=1.5pt]{-5}{0.10}{(-2*x+8)/(2*x-2)}%
  \def\function{ -2 xVal mul 8 add 2 xVal mul -2 add div }%
  \pstVerb{ /xVal 0 def }% start value
  \multido{\nA=0+1}{4}{%
    \psline[linecolor=blue,linewidth=1.5pt]{->}(! xVal xVal )(! xVal
\function )
    \psline[linecolor=blue,linewidth=1.5pt]{->}(! xVal \function )(!
\function\space dup)
    \pstVerb{ /xVal \function\space def}
    \psline[linestyle=dashed,linecolor=blue]{->}(! xVal xVal)(! xVal 0 )
    \uput{1ex}[90](! xVal 0 ){$v_{\nA}$}
  }
\end{pspicture}
\end{center}

\end{document}


Herbert