In ConTeXt the ampersand is not an alignment character but has catcode
12 by default.  Use the "ampersand replacement" option.

\usemodule[tikz]
\usetikzlibrary[matrix,decorations.pathreplacing, calc, positioning,fit]
\starttext

\starttikzpicture[>=stealth,thick,baseline,
every right delimiter/.append style={name=rd},
]
\matrix [matrix of math nodes,
    left delimiter=(,
    right delimiter=),
    ampersand replacement=\&
    ](A){
a_{1,1} \& a_{1,2} \& \dots  \& a_{1,j} \& \dots \& a_{1,n}\\
a_{2,1} \& a_{2,2} \& \dots  \& a_{2,j} \& \dots \& a_{2,n}\\
\vdots  \& \vdots  \&  \& \vdots  \&  \& \vdots\\
a_{i,1} \& a_{i,2} \& \dots  \& a_{i,j} \& \dots \& a_{i,n}\\
\vdots  \& \vdots  \&  \& \vdots  \&  \& \vdots\\
a_{n,1} \& a_{n,2} \& \dots  \& a_{n,j} \& \dots \& a_{n,n}\\
};

\draw[<-] (rd)--++(0:6mm) node[right]{$i$-ième colonne};
\draw[<-] (A.south-|A-1-4.center) --++(-90:6mm) node[below]{$j$-ième
colonne};

\stoptikzpicture
\stoptext



On 4/18/19 9:26 PM, Fabrice Couvreur wrote:
> Hi,
> If I compile the following code, the result is not the one expected.
>
> \usemodule[tikz]
> \usetikzlibrary[matrix,decorations.pathreplacing, calc, positioning,fit]
> \starttext
>
> \starttikzpicture[>=stealth,thick,baseline,
> every right delimiter/.append style={name=rd},
> ]
> \matrix [matrix of math nodes,
>     left delimiter=(,
>     right delimiter=),
>     ](A){
> a_{1,1} & a_{1,2} & \dots  & a_{1,j} & \dots & a_{1,n}\\
> a_{2,1} & a_{2,2} & \dots  & a_{2,j} & \dots & a_{2,n}\\
> \vdots  & \vdots  &  & \vdots  &  & \vdots\\
> a_{i,1} & a_{i,2} & \dots  & a_{i,j} & \dots & a_{i,n}\\
> \vdots  & \vdots  &  & \vdots  &  & \vdots\\
> a_{n,1} & a_{n,2} & \dots  & a_{n,j} & \dots & a_{n,n}\\
> };
>
> \draw[<-] (rd)--++(0:6mm) node[right]{$i$-ième colonne};
> \draw[<-] (A.south-|A-1-4.center) --++(-90:6mm) node[below]{$j$-ième
> colonne};
>
> \stoptikzpicture
> \stoptext
>
> Thank you
> Fabrice
>
>
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to the Wiki!
>
> maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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> ___________________________________________________________________________________
>

___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________