Re: Very slow ploting with gnu plot (windows)

[Ben Abbott]

On Nov 22, 2012, at 5:09 AM, Matej Froebe wrote:

> Hi,
> 
> I have a problem with gnuplot under Octave 3.6.2 (Windows, pre-compiled
> versions of Octave-3.6.2 for Microsoft Visual Studio).
> 
> Ploting of large Data with gnuplot takes apoximately four times as long as
> it did with version 3.2.4 (installation file
> Octave-3.2.4_i686-pc-mingw32_gcc-4.4.0_setup.exe).
> 
> For example:
> 
> testVect=rand(500000, 1);
> plot(testVect)
> 
> 
> In version 3.6.2 this example takes about 40s and in version 3.2.4 about
> 12s.

Octave 3.6.2 switched to using ghostscript to convert from eps to bitmapped 
formats.  This *may* be the cause of the slow down you are experiencing.  You 
can confirm by timing "print test.eps" and "print test.png" and them compare 
the differences.

        close all
        graphics_toolkit gnuplot
        plot (rand (3))
        tic ()
        print test.eps
        gnuplot_eps = toc ()
        tic ()
        print test.png
        gnuplot_png = toc ()

        close all
        graphics_toolkit fltk
        plot (rand (3))
        tic ()
        print test.eps
        fltk_eps = toc ()
        tic ()
        print test.png
        fltk_png = toc ()

Please run this script and let us know what the result is.

> Ploting with other graphics toolkits is much faster, but there are problems
> with converting of plots to images.


Ghostscript is used for both the gnuplot and fltk backends.  So there should be 
no difference in the ability to produces images for these two toolkits.  If 
there is a difference in how long it takes to print, the problem will be with 
producing the eps-file.

Printing using the "qt" toolkit is not yet supported.

Ben