[Octave-bug-tracker] [bug #34549] imshow chokes when displaying an imaginary image with no limits

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?34549>

                 Summary: imshow chokes when displaying an imaginary image
with no limits
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Fri 14 Oct 2011 03:04:40 PM UTC
                Category: Interpreter
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Richard Milne
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.2.3
        Operating System: GNU/Linux

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Details:

The attached script and image reproduce my error.

What I do or don't expect:

1. Maybe my understanding of the theory or the octave commands is hazy, but
all the figures/matrices I'm trying to plot are real matrices. Why, then, when
I calculate the log of such a matrix, do I get imaginary numbers back?

In other words, I don't expect the message:
"warning: imshow: only showing real part of complex image"

2. A larger, concern, however, is why the command on line 16 doesn't run
properly. Why doesn't this command work, when the three similar ones before it
do?

3. The command seems to work when I manually calculate the limits for the
imshow parameter. But I was expecting more from the resulting image than a
uniform grey picture. Again, problem with octave, or my understanding of the
theory?

====
Here are the details of my system, running on an HP EliteBook 8560w:


$ cat /etc/lsb-release 
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=10.04
DISTRIB_CODENAME=lucid
DISTRIB_DESCRIPTION="Ubuntu 10.04.3 LTS"

$ octave

octave:1> ver
----------------------------------------------------------------------
GNU Octave Version 3.2.3
GNU Octave License: GNU General Public License
Operating System: Linux 2.6.32-34-generic #77-Ubuntu SMP Tue Sep 13 19:40:53
UTC 2011 i686
----------------------------------------------------------------------
Package Name  | Version | Installation directory
--------------+---------+-----------------------
       image *|  1.0.15 | /usr/share/octave/packages/3.2/image-1.0.15




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File Attachments:


-------------------------------------------------------
Date: Fri 14 Oct 2011 03:04:40 PM UTC  Name: bugreport.m  Size: 527B   By:
None

<http://savannah.gnu.org/bugs/download.php?file_id=24149>
-------------------------------------------------------
Date: Fri 14 Oct 2011 03:04:40 PM UTC  Name: image1.tif  Size: 257kB   By:
None

<http://savannah.gnu.org/bugs/download.php?file_id=24150>

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