How do I make a log-log plot?



>>>>> "Jon" == Jon B <3ujg84402@sneakemail.com> writes:

    Jon> Hi.  I can't figure out how to make a good log-log plot in Maxima (x
    Jon> and y axis are both 1, 10, 100, 1000, ... instead of 1, 2, 3, ...)

    Jon> I've figured out how to use [gnuplot_preamble, "set log xy"] to get
    Jon> the gnuplot axes log spaced, but it seems like maxima is feeding it
    Jon> data points that are linearly spaced and then gnuplot connects them
    Jon> with straight lines.  The beginning of the plot looks like spread-out

Can you give an example of this?

    Jon> points with straight lines connecting them while the end of the plot
    Jon> looks like it has more data points than necessary, and the lines are
    Jon> all crammed together.

I think I know why this is.  plot2d doesn't really know about log
plots and assumes, more or less, uniform sampling of the function.  So
there won't be as many points in 1-10 as there are in 10-100.

I guess we would need to tell plot2d that we're doing a log plot and
have it sample logarithmically to get uniform sampling of the plot.

You might be able to specify a larger nticks value to help smooth out
your plots.

    Jon> Where can I find detailed documentation for the plot2d command?

You have to read the code in src/plot.lisp, I think.

Ray