[Octave-bug-tracker] [bug #55876] Can not correctly set ylim sometimes in log plot

[Eddy]

URL:
  <https://savannah.gnu.org/bugs/?55876>

                 Summary: Can not correctly set ylim sometimes in log plot
                 Project: GNU Octave
            Submitted by: count
            Submitted on: Sun 10 Mar 2019 02:56:55 PM UTC
                Category: Plotting
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: Any

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Details:

An example is:
(Octave version 5.0.91 built from source, Debian 9):


1> semilogy (logspace (-30, 1, 100))
2> ylim ([2e-27   3e-13])
3> ylim ()
ans =

   2.0000e-29   3.0000e-11

4> set (gca, 'ytick', [1e-25   1e-20]);  % slow here
5> ylim ()
ans =

   2.0000e-31   3.0000e-09

6> length (get (gca, 'yminortickvalues'))
ans =  27000287


Setting of ylim lead to different bounds, and the bounds could change due to
setting of 'ytick'. Also the minor ticks after setting ytick is weird.

This happens in version 4.4.1 and 5.1.0 also, although the detailed behavior
may be different. Seems no problem in version 4.0.3.

A probably related bug is: after the semilogy above, try zooming into small
range using GUI (say fltk). The zoom in y direction would be "blocked" up to
some scale (say 10^-16 ~ 10^-8), i.e. cannot zoom in too much.

Due to this bug, I sometimes could not workaround bug #55864 by manually
setting axis ticks.




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