Fri 10 Nov 2017 06:10:34 AM UTC, comment #10:
This bug report is against a deprecated and no longer supported version of Octave. It also appears to be related to individual hardware. I'm going to close this report, but a new one can be opened if the problem can be reproduced, with more detail, using a more recent version of Octave.
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Wed 14 Sep 2016 02:58:41 PM UTC, comment #9:
When I reported this bug, I did not realize how complicated the issue would get. I have now tested a second computer and I was not able to reproduce the bug. This second computer is running the same nvidia driver. Both computers are using GTX 980 TI GPUs, although they are from different manufacturers. Both computers are running Windows 10.
I am not familiar with gdb. When the bug occurs the systems ask to start Visual Studio, which I do. But without a symbol file for opengl32.dll, all I can get is that there is an unhandled exception. How would gdb do any better?
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Sat 10 Sep 2016 09:58:28 PM UTC, comment #8:
The color scale is an expected change in 4.2, see "news".
OpenGL is a mature standard, but there are many vendor-specific implementations of the library, at least on GNU systems, not sure about Windows. There are several open bug reports for Octave crashes on GNU systems with various specific video drivers. The crash that you are seeing may be dependent on your specific video chip.
You can use the gdb debugger that is installed in Octave's bin directory, if you are familiar with gdb.
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Sat 10 Sep 2016 08:34:06 PM UTC, comment #7:
I have installed Octave 4.2 RC1. The crash problem still exists with the Qt toolkit. There was one other difference when running the gnuplot toolkit. The color scale for the images has changed. In 4.0.1 the colors in the image range from deep blue to red. In 4.2 the colors range from deep blue to yellow. The range of the numbers on the scales did not change.
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Fri 09 Sep 2016 12:47:02 PM UTC, comment #6:
Stephen, a first release candidate for Octave 4.2 is available here:
ftp://alpha.gnu.org/gnu/octave/
Could you please try whether this still crashes on imagesc with qt for you?
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Sun 04 Sep 2016 07:50:28 PM UTC, comment #5:
I am using opengl32.dll version 10.0.10586.0. I don't understand why I can't download the pbd file from the Microsoft symbol servers as this seems to be a Microsoft DLL.
It seems strange that there would be any unhandled exceptions in OpenGL, as this is a mature product.
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Sun 04 Sep 2016 07:06:41 PM UTC, comment #4:
I started the CLI and checked out both 'qt' and 'fltk'. With 'fltk' active I get very nice plots. With 'qt' active, Octave will crash with no error messages, but there is an option to debug. If I start the debugger (VS2015) I get
Unhandled exception at 0x6BD140F8 (opengl32.dll) in octave-gui.exe: 0xC0000005: Access violation writing location 0xA7408167.
I can't debug without opengl32.pbd.
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Sun 04 Sep 2016 05:31:39 AM UTC, comment #3:
'imagesc' should be working with any of the three toolkits available in Octave. Both 'qt' and 'fltk' use OpenGL to render the graphics. 'gnuplot' calls the external program.
Afaik there is not (yet) any comprehensive comparison of the different features of the three toolkits. Main differences are that the OpenGL toolkits always store pixel graphics whereas 'gnuplot' stores vector graphics if the file format supports it. But best try which one works best for you, I guess...
It would be interesting if you please tried to run your program (with 'qt') without the GUI by starting Octave with 'octave-cli'? Maybe this could give you some error messages that could help some developer to fix the problem you are seeing.
You can change the graphics_toolkit you are using permanently by adding the appropriate line to your startup script. I can't remember now where this is stored in Windows (writing from my mobile). Maybe you can find the location of it in the PDF or on the Wiki (or someone who knows can jump in).
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Sun 04 Sep 2016 01:24:21 AM UTC, comment #2:
I have tried the commands you suggested and the plotting works after either one. I am guessing I must load one of these graphics toolkits before using imagesc? I tried restarting Octave and it did not remember the last graphics toolkit that I used. Is there some way to automatically load a graphics toolkit when Octave starts? After searching inline docs about these toolkits, I found that Octave is starting with the qt toolkit. I guess this toolkit does not support the imagesc command. Is one toolkit better than another?
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Fri 02 Sep 2016 07:56:57 PM UTC, comment #1:
I cannot reproduce the crash with your examples on Windows 10 with Octave 4.0.3 or a current tip (hg id 7e152b7c2a2c).
Which graphics_toolkit are you using?
Can you please try to execute
or
and run your example again after each of the above lines?
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Tue 09 Aug 2016 11:13:45 PM UTC, original submission:
I am using Windows 10. I stepped through the program and everything seems to work fine up until the point where I call imagesc. At that point Octave gives the option to debug or close the program. I have attached the two scripts and the data file. I have also tried using image and imshow and it still crashes.
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