[Octave-bug-tracker] [bug #59370] Plotting produces wrong output or takes long time, depending on graphics toolkit

[T Knauss]

URL:
  <https://savannah.gnu.org/bugs/?59370>

                 Summary: Plotting produces wrong output or takes long time,
depending on graphics toolkit
                 Project: GNU Octave
            Submitted by: tknauss
            Submitted on: Tue 27 Oct 2020 04:45:04 PM UTC
                Category: Plotting with OpenGL
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: 5.2.0
         Discussion Lock: Any
        Operating System: Microsoft Windows

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Details:

1) Create a Matrix from these values:
S = [0.966087133253521, 
0.966087134195414, 
0.966087134195414, 
0.966087148503056, 
0.966087148503056, 
0.966087174908003, 
0.966087174908004, 
0.966087191418938, 
0.966087191418939, 
0.966087204808544, 
0.966087204808545, 
0.966087204808545, 
0.966087204808545, 
0.966087204808545, 
0.966087204808545, 
0.966087204808545, 
0.966087204808545, 
0.966087204808545, 
0.966087204808545, 
0.966087204808545, 
0.966087204808545, 
0.966087204808545, 
0.966087204808545, 
0.966087204808545, 
0.966087204808545, 
0.966087204808546, 
0.966087204808546, 
0.966087204808546, 
0.966087204808546, 
0.966087204808546, 
0.966087204808546, 
0.966087204808546, 
0.966087204808546, 
0.966087204808546, 
0.966087217807083, 
0.966087217807083]

2) Execute "plot(S)".

If the graphics toolkit is "qt" (seems to be the default, queried after the
first test), the output is wrong. See attached screenshot.
If the graphics toolkit is "gnuplot" (chosen before the next test), the output
seems to be correct, but it takes about 10 seconds with full load on 1 CPU
core and about 30 more seconds with no CPU activity until the plot is
displayed.
In "fltk", it seems to be correct and is shown instantly.
After switching back to "qt", the output seems to be correct, too, but it also
takes time now.

Actually, it seems to become slower after every change of the graphics
toolkit.

The behaviour can be reproduced by restarting Octave. The delay is not always
reproducible.




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File Attachments:


-------------------------------------------------------
Date: Tue 27 Oct 2020 04:45:04 PM UTC  Name: octave@bug@-@plot(S)@with@qt.png 
Size: 9KiB   By: tknauss

<http://savannah.gnu.org/bugs/download.php?file_id=50138>

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