pstricks problem

[Denis Girou]

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The following message is a courtesy copy of an article
that has been posted to comp.text.tex as well.

>>>>> "Frank.Mueller" == Frank Mueller <meckccef at sp.zrz.tu-berlin.de> writes:

    Frank.Mueller> I use the pstricks package (including pst-node) to draw some
    Frank.Mueller> graphics. Why isn't the result of the following code an arrow,
    Frank.Mueller> positioned between the nodes? Instead, it appears to the upper
    Frank.Mueller> left of the graphic.
    Frank.Mueller>    If I use the command "ncline" instead of "ncLine", the arrow
    Frank.Mueller> gets to the (in the sense of "ncline") right position. I'd like a
    Frank.Mueller> centering relative to the centers of the nodes, not to the
    Frank.Mueller> borders.
    Frank.Mueller> %
    Frank.Mueller> % ---snip---

    Frank.Mueller> \documentclass{article}
    Frank.Mueller> \usepackage{pstricks}
    Frank.Mueller> \usepackage{pst-node}
    Frank.Mueller> \begin{document}
    Frank.Mueller> \begin{pspicture}(10,10)
    Frank.Mueller>   \pnode(2,5){Pin1}
    Frank.Mueller>   \pnode(8,5){Pin2}
    Frank.Mueller>   \ncLine{Pin1}{Pin2}
    Frank.Mueller>   \mput{\Large $\Rightarrow$}
    Frank.Mueller> \end{pspicture}
    Frank.Mueller> \end{document}

    Frank.Mueller> % ---snap---
    Frank.Mueller> %
    Frank.Mueller> % What could be the reason?

  This is a bug in the `pst-node' package (but very easy to solve). In fact,
it is a very old one, which was introduced in 1994 in the pst-beta.tex file
(used to build the PSTricks 97 distribution) as I verify that it doesn't
affect the pst-node.tex file of the 0.93a distribution but the rewriting of
the \ncLine at ii macro in the pst-beta.tex file.

  P.S. * Take care that the \mput macro was already declared obsolete in 1994
(betadoc2.ps documentation file, page 32). Use better \ncput, etc. today.

       * You can consider to use the "psmatrix" environment, which offer
a powerful way to build diagrams with nodes and connections (but it depend of
what you have to do).

  Thanks for the report. Correction is included below:

\documentclass{article}

\usepackage{pst-node}

\pagestyle{empty}

\begin{document}

\psset{subgriddiv=0,linecolor=red,linewidth=0.1}

\begin{pspicture}(5,5)\psgrid
  \pnode(1,4){Pin1}
  \pnode(4,4){Pin2}
  \ncLine{Pin1}{Pin2}
  \mput{\Large $\Rightarrow$}
\end{pspicture}

\vspace{2cm}

\makeatletter
\def\ncLine at ii#1#2{\nc at object{Open}{#1}{#2}{.5}%
% D.G. modification begin - Apr. 14, 1999
%{\tx at NCLine /LPutPos { xB xA yB yA \tx at LPutLine } def}}
{\tx at NCLine /LPutPos { xB yB xA yA \tx at LPutLine } def}}
% D.G. modification end
\makeatother

\begin{pspicture}(5,5)\psgrid
  \pnode(1,4){Pin1}
  \pnode(4,4){Pin2}
  \ncLine{Pin1}{Pin2}
  \mput{\Large $\Rightarrow$}
\end{pspicture}
\hfill
\begin{pspicture}(5,5)\psgrid
  \pnode(1,4){Pin1}
  \pnode(4,4){Pin2}
  \ncLine{Pin1}{Pin2}
  \ncput{\Large $\Rightarrow$}
\end{pspicture}

\end{document}

Denis Girou
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