Subject: Fwd: [Maxima] Re: How do I make a log-log plot?
From: Robert Dodier
Date: Wed, 27 Jul 2005 09:43:45 -0600
On 7/20/05, Raymond Toy wrote:
> I was basically lazy. I think a suitable interface is as you
> suggest. logx and/or logy means you want a logarithmic plot of some
> kind, and it should set the appropriate options for the underlying
> plotting program, if necessary.
>
> It's a bit of a pain though, especially for gnuplot, since the gnuplot
> options are just a bunch of strings suitable for gnuplot. And what
> about the other plotting programs? I never use anything except
> gnuplot, so I don't know how the others work.
Well, the plotting programs which are supported by Maxima
are some subset of gnuplot, openmath, geomview, zic, xgraph,
and a built-in postscript output. (There is code for geomview and
zic in src/plot.lisp, but those are not mentioned in the manual.
There are some functions to create xgraph output but it is not
recognized as a valid selection for plot_format.) I am aware
that some of these might be officially unsupported.
Of these, gnuplot and xgraph definitely have built-in support for
logarithmic plots. openmath and the built-in postscript output
appear to lack it (to judge by scanning src/plot.lisp and
plotting/omplotdata). I don't know about geomview and zic.
At this point my recommendation is to turn on the gnuplot
option for a logarithmic plot when plot2d is given the log plot
option and the plot_format is gnuplot or mgnuplot,
and otherwise print a warning message and carry out the
log transform in plot.lisp (i.e., plot f(log(x)) instead of f(x)).
For what it's worth,
Robert Dodier