Debug plotting issues
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- Octave version: Execute 'ver' in Octave and copy "GNU Octave Version" and "Operating System" verbatim. If you are on Windows please mention which build (MinGW, Cygwin, MXE, Visual Studio see Octave for Microsoft Windows) and where you got it (download from https://sourceforge.net/, http://mxeoctave.osuv.de/) or have you build it yourself?. This is important because some packages includes whole build environment while other just provide binaries even for octave-forge packages.
- Operating system:
- Windows: Is it XP 32bit or 64bit? Windows 7 or 8?
- GNU/Linux: Have you installed Octave using your package system (apt-get, yum..) or compiled from source tarball?
- If you get a warning on startup, for example "warning: function xyz.m shadows a built-in function" please copy it verbatim
- If you get an error message, please, please, please copy the message verbatim
I can't plot or print or the output doesn't look as expected
Please create a simple, as small as possible example which shows the problem so others can reproduce the problem on their system and help you. Upload a screenshot (together with the script) if you can't describe it with words.
- Sometimes the figure on the screen visually differs from the file generated with "print". If this is the case please mention this and consider adding a screenshot of the figure window together with the generated print.
- Which toolkit are you using? Common toolkits are 'fltk' (which is default now) or 'gnuplot'. Consider switching to another available toolkit (see available_graphics_toolkits) and try it there. You have to execute (for example switch to gnuplot) 'graphics_toolkit gnuplot' before any plotting command.
- Which Ghostscript version do you use? Is it a 32 or 64bit build? Please add URL to download. If 64bit under Windows see Octave for Microsoft Windows#Printing (installing Ghostscript)
Debug printing with gnuplot
and attach the generated octave-print-commands.log, debug message and testplot.eps.
Debug printing with fltk
The output of commands described here were created with a GNU/Linux system. Windows or MacOS builds may differ. Please update the article if you find any differences.
The class opengl_renderer is used to render a graphics_object to an OpenGL context. If you use the "print" command with graphics_toolkit fltk, gl2ps is used to capture these OpenGL drawing commands and translates them to Encapsulated PostScript (EPS). If you have requested a different output format than EPS, the EPS output of gl2ps is then piped to ghostscript (gs) which does the conversion to PDF, PNG, JPG ...
You can see the pipleline to ghostscript by adding "-debug" to the "print" command:
|Code: print with "-debug"|
octave:1> sombrero octave:2> print("-dpng", "out.png", "-debug") Ghostscript command: '/usr/bin/gs -dQUIET -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -dTextAlphaBits=4 -dGraphicsAlphaBits=4 -r150x150 -dEPSCrop -sOutputFile="out.png" -' fltk-pipeline: '/usr/bin/gs -dQUIET -dNOPAUSE -dBATCH -dSAFER -sDEVICE=png16m -dTextAlphaBits=4 -dGraphicsAlphaBits=4 -r150x150 -dEPSCrop -sOutputFile="out.png" -'
For debugging purposes it may be desired to have the direct output of gl2ps without piping them through ghostscript.
This can simply be done with
print -depsc out.eps
or if you prefer a black/white output:
print -deps out.eps
If you want to wiretap the output of gl2ps, which is meant to go to ghostscript if printing a PNG, JPG etc. it's a little bit more complicated because the existence of the ghostscript binary is checked first. Therefore simply replacing the ghostscript binary
print -dpng "-Gcat > debug.eps" out.eps
won't work. A hack is to create a shell script (myredirect.sh in my case ) which does the redirection:
#!/bin/bash rm debug.eps while read x ; do echo $x >> debug.eps ; done
Which can then be used with
print -dpng "-G./myredirect.sh" out.eps
Another way is to directly use the opengl_renderer to draw to gl2ps. paperposition, papersize and so on are ignored in this case.
drawnow ("eps", "cat > out.eps")
For 2D plots a simpler algorithm(GL2PS_SIMPLE_SORT) is choosen but you can force this also for 3D plots:
drawnow ("epsis2d", "cat > out.eps")
some Windows issues
- A user had problems printing with fltk in windows. After he updated the graphic drivers the problem was gone. http://octave.1599824.n4.nabble.com/Problem-with-Print-under-Octave-3-8-1-under-windows-tp4664755.html
Please see also the FAQ
- A common problem is that printing with fltk only works if the figure is visible, see 
|Code: FLTK printing test script|
close all graphics_toolkit fltk h = plot ([0, 0.5, 1], [0, 0.5, 1], '-sb'); set (h, 'markerfacecolor', 'b', 'markersize', 20, 'linewidth', 4) hold all h = plot ([1, 0.5, 0], [0, 0.5, 1], '-or'); set (h, 'markerfacecolor', 'r', 'markersize', 20, 'linewidth', 4) set (gca (), 'color', 'c') title ('Cyan background, black axes. A red line with circle markers above a blue line with square markers.') print -depsc junk1.eps # Bug 35648, is this a representive test for this? What is the desired output? close all hp = patch([1 1 2 2],[1 2 2 1], [1 0.8 1]); grid on; set(gca,'layer','bottom'); title ('Please describe what we should see') print -depsc junk2.eps