[Maxima] Multiple maxima instances and maxout.gnuplot_pipes
biomates at telefonica.net
Tue Apr 22 12:37:04 CDT 2008
Raymond Toy (RT/EUS) escribió:
> Robert Dodier wrote:
>> On 4/22/08, Dan Hatton <vi5u0-maxima at yahoo.co.uk> wrote:
>>> I currently have four instances of Maxima running on different
>>> computers, on all of which I have the same home directory via NFS.
>>> The four are all running batch scripts that involve plot2d commands.
>>> Am I likely to encounter any problems due to them clashing over trying
>>> to write to the same maxout.gnuplot_pipes file, or is there some
>>> automated handling for this situation?
>> Maxima doesn't try to avoid file name collisions, though doubtless it should.
> I'm not really familiar with how gnuplot_pipes work, but it seems maxima
> has a pipe open to gnuplot over which we can send commands. Maybe it
> would be possible to send the data over the pipe as well instead of
> writing the data to maxout.gnuplot_pipes.
This is just how package draw worked in some of the first experimental
versions. But problems began when great amounts of data were sent to
gnuplot (cartographic maps, images).
At this moment, when one makes use of draw, two files are generated:
maxout.gnuplot (the gnuplot commands) and data.gnuplot (the data) and
the draw routine sends to gnuplot only one command via the pipe: 'load
Why two files? Because the alternative exists that data (at least some
sort of data) can be stored in binary files to be read by gnuplot; but
this is not yet implemented in draw.
> Then the processes are completely independent, and we don't have to cook
> up random file names.
There are two global variables defined in draw (Maxima 5.15):
gnuplot_file_name (default is string "maxout.gnuplot") and
data_file_name (default "data.gnuplot"). Maybe the original poster can
find them useful. I make intensive use of them in a maxima web interface
(by the way, based on lisp-cgi-utils), where different users want to
make different plots at the same time.
Mario Rodriguez Riotorto
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