Octave taking too long to save image files

Question

I'm running Octave 3.8.1 on a i3 2GB DDR3 RAM powered notebook within Ubuntu 14.04 on dualboot with Windows 7.

And I'm having a really hardtime saving plots that I use on my seismologic research, they are quite simple and still I wait almost 5 min to save a single plot, the plot is built within seconds, the saving though...

Is it purely a problem with my notebook performance? When I run a program for the first time I get the following warnings on shadowed functions, has one of them anything to do with it?

warning: function /home/michel/octave/specfun-1.1.0/x86_64-pc-linux-gnu-api-v49+/ellipj.oct shadows a built-in function
warning: function /home/michel/octave/specfun-1.1.0/erfcinv.m shadows a built-in function
warning: function /home/michel/octave/specfun-1.1.0/ellipke.m shadows a core library function
warning: function /home/michel/octave/specfun-1.1.0/expint.m shadows a core library function

Also, this started to happen when I upgraded from a very old version of Octave (2.8 if I'm not mistaken), it seems that the old one used to run on the linux default plot making functions, and the new one (3.8.1) runs on its own, is it correct? I used to take a little more time with this notebook that I take with the lab PC, but not even close to 5min+ for each plot.

Is there anything I can do, like upgrading anything within the octave or "unshadowing" the functions mentioned before?

Thanks a lot for the help.

Answer 1

Shadowing functions is just a name clash which is explained for example here: Warnings after octave installation

As for low performance, octave renderer doesn't seem to be well optimized for writing plots with huge number of points. For example, the following:

tic; x=1:10000; plot(sin(x)); saveas(gcf,'2123.png'); toc;

Will put octave in coma for quite a while. Even though the plot itself is made in an instant. If amounts of your data are of comparable magnitude, consider making it more sparce prior putting it on the graph.

There's no default linux plotmaker, there's gnuplot. You may try your luck with it by invoking

graphics_toolkit gnuplot

before plotting. (To me it didn't do much good though. graphics_toolkit fltk will return octave's usual plotter.)

If the slowness you refer to is in saving three dimensional plots (like mesh), the only workaround I've found on system similar to your is to use alt+prtscr.

Alternatively, you could try obtaining octave 4.0 which is released by now. It's changelogs mention yet another graphics toolkit.