Execution and Plot times for 1Kx1K ambiguity function

[John W. Eaton]

On 29-Jul-2008, Labitt, Bruce wrote:

| Matlab plots the mesh plot within 5 additional seconds on my laptop,
| Octave through gnuplot has not been able to plot anything yet to the
| screen.  
| 
| If I run top I see gnuplot at 100% CPU and 7% memory.  gnuplot has been
| running for 37 minutes now and has not rendered the figure.
| 
| Anyone got an idea on how to diagnose this "slowness" and to hopefully
| fix this?  I've got much larger problems to solve than this, so the
| speed difference is an issue.  I realize this is just the problem
| statement.  What else should I provide the list (or select others) to
| help the analysis?

If you issue the command

  figure (1, "visible", "off");

before running your script, then it will set up the plot but not
actually ask gnuplot to plot it.  Then you can run

  drawnow ("x11", "/dev/null", 0, "debug.gp");

and Octave will generate a file "debug.gp" that contains the commands
it sends to gnuplot.  When I do this with your code, I get a file that
is approximately 69MB.  I guess it takes a while for gnuplot to
process that.

I suppose Octave could try to process the data before sending it to
gnuplot so that gnuplot has less work to do, but it is not always
clear when that is an appropriate thing to do.  And in any case, I'm
not sure that it is worth much effort to try to improve the interface
to gnuplot since we are moving away from gnuplot anyway.

jwe