plotting and solving inequalities



> There are examples about this in
> http://www.telefonica.net/web2/biomates/maxima/gpdraw/
> 

That is a nice and useful interface to gnuplot, but i see that 
you set the x range explicitly in your examples.
I would like to enter the command 
 
 plot2d(x/(x^2-4));

to display a plot, say, in the xrange [-3,3] and yrange [-6,6]
(that is in the range needed to get the main pattern of the function,
where relative changes are over a threshold - the first derivative 
could help to assess such range)
and two vertical dotted lines at x=+2 x=-2.

How it that possible using draw2d?

I have loaded your  draw.lisp  in maxima (version 5.10) but it fails o
execute your example command (see below).
Probably i should upgrade my maxima program

thank you for you help

--
Pol

---- enc

(%i8) draw2d(explicit(u^2,u,-3,3))$

  Maxima encountered a Lisp error:

   Error in COND [or a callee]: The function CHECK-GNUPLOT-PROCESS is
undefined.

   Automatically continuing.
   To reenable the Lisp debugger set *debugger-hook* to nil.

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