[pstricks] How to show a specific point of a function's curve?

[Herbert Voss]

Am 24.01.2011 16:06, schrieb Denis Bitouzé:
> Le lundi 24/01/11 à 15h40,
> Herbert Voss <Herbert.Voss at fu-berlin.de> a écrit :
> 
>> in general yes, but the problem is that we already have tons
>> of macros and nobody really knows all names and meanings ...
> 
> Indeed, but such a macro would be very useful and, restricted to
> pst-plot, wouldn't be lost in tons of others. IMHO, this macro would be
> much more useful to the average user than, for instance, LineToXAxis and
> LineToYAxis (which are nice! :)...

this maybe possible, it's really simple. Would be part of pst-plot

\documentclass{article}
\usepackage{pst-plot}
\makeatletter
\def\psCoordinates{\pst at object{psCoordinates}}
\def\psCoordinates at i(#1){%
  \pst at killglue%
  \begin at OpenObj
  \SpecialCoor%
  \psline(#1|0,0)(#1)\psline(#1)(0,0|#1)\psdot(#1)%
  \end at OpenObj%
  \ignorespaces%
}
\pagestyle{empty}
%
\makeatother
\begin{document}
\begin{pspicture}(10,10)
  \psaxes{->}(10,10)
  \psplot[algebraic,linecolor=red,linewidth=2pt]{0}{10}{x^2/10}
  \psCoordinates(*2 {x^2/10})
  \psCoordinates[linecolor=blue,linestyle=dashed,
     dotstyle=square,dotscale=2](*4 {x^2/10})
  \psCoordinates[arrows=->,linecolor=blue,linestyle=dotted,
     dotstyle=triangle,dotscale=2](*8 {x^2/10})
\end{pspicture}

\end{document}

Herbert
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