Re: [Maxima-discuss] How to use a graphviz program in the draw_graph function

[Michel T. <ta...@lp...>]

Le 24/06/2017 à 08:38, Hans-Peter Vietze a écrit :
> I tried to use one of the graphviz functions to visualize a graph, but 
> did not succeed. I tried the attempt of Michel Talon but got an error 
> message:
> 
>   -->
> Nachricht vom stdout von wxMaxima: Maxima 5.39.0_2_g5a49f11_dirty 
> http://maxima.sourceforge.net
>      using Lisp CLISP 2.49 (2010-07-07)
>      Distributed under the GNU Public License. See the file COPYING.
>      Dedicated to the memory of William Schelter.
>      The function bug_report() provides bug reporting information.
> (%i1)
>   -->    load(graphs);
> 0 errors, 0 warnings
>      0 errors, 0 warnings
> (%o1) 
> "C:\maxima-5.39.0\share\maxima\5.39.0_2_g5a49f11_dirty\share\graphs\graphs.mac" 
> 
>   --> 
> g:create_graph(16,[[0,1],[1,3],[2,3],[0,2],[3,4],[2,4],[5,6],[6,4],[4,7],[6,7],[7,8],[7,10],[7,11],[8,10],[11,10],[8,9],[11,12],[9,15],[12,13],[10,14],[15,14],[13,14]]); 
> 
> (g)    GRAPH\(16 vertices, 22 edges\)
>   -->    mi:max_independent_set(g);
> (mi)    [0,3,5,8,11,13,15]
>   -->    draw_graph(g,redraw=true,program=dot);
> first: empty argument.
>      #0: draw_graph(g=GRAPH\(16\ vertices\,\ 22\ edges\),options=[redraw 
> = true,program = dot]) 
> (C:\maxima-5.39.0\share\maxima\5.39.0_2_g5a49f11_dirty\share\graphs\draw_graph.mac 
> line 166)
>       -- an error. To debug this try: debugmode(true);
>      Message from maxima's stderr stream: Der Befehl "dot" ist entweder 
> falsch geschrieben oder
>      konnte nicht gefunden werden.


I have tried several examples of the documentation for draw_graph and 
they work for me, that is a windows appears with the graph drawn. 
However i am under Linux and using sbcl, while you are using clisp and
Windows.

In fact your program works on my machine.  I see first a compilation of
numericalio, and the the graph is drawn.

One remark: against localization of programs. With localization, when
an error message appears, it is localized, and thus impossible to 
understand precisely for someone who doesn't speak the language. For an 
open source software this limits the number of people who can help.
English is "lingua franca" for scientific stuff, and allows everyone to 
collaborate.

Second: the error at line 166 of draw_graph.mac is not directly related 
to dot. The line says
dimension : length(second(first(v_pos)))
which is coherent with
first: empty argument
in other words v_pos is undefined when first is called. But just before 
one has
v_pos : apply(program, [G]),
set_positions(v_pos, G)),
I don't know what is set_positions, it is not defined in the file.

Anyways probably your maxima cannot find the dot program. It is called 
this way:
if program = 'dot then
     command : concat("dot -Tplain \"",
       gp_file_in, "\" > \"", gp_file_out, "\"")
...
system(command),

So the invocation
system("dot -Tplain ...") has to succeed. Probably dot has to be in your 
path in Windows and perhaps more. The syntax to call external programs 
may vary from lisp to lisp, and something which works with sbcl may not 
work with clisp. Note it is the path variable of windows which is 
impoirtant here, not the file_search_maxima path list.



-- 
Michel Talon