The package allows the user to use the computer algebra system XCAS 
to generate tables of signs and of variations (the actual plotting of
the tables uses the MetaPost macro package "tableauVariation.mp" :

http://frederic.mazoit.free.fr/LaTeX_metapost/tableauVariations/ . 

The tablor package requires that shell escape be enabled.


For instance :

\begin{TV} TV([-10,+infinity],[-1,1],"g","t",x^2/(x^2-1),1,\tv) \end{TV} 

draws table of  variations  of  x->x^2/(x^2-1). 


You can download XCAS here:


http://www-fourier.ujf-grenoble.fr/%7Eparisse/giac.html


The     non-french     users    need     to     comment    out     every

" \usepackage[upright]{fourier} "

Just put tablor.sty and tablor.cfg into /texmf/tex/latex/tablor/