bugGNU Octave - Bugs: bug #32836, quiver3 draws nothing, although it...

 
 

bug #32836: quiver3 draws nothing, although it should

Submitter:  None
Submitted:  Fri 18 Mar 2011 03:46:29 PM UTC
   
 
Category:  Plotting Severity:  3 - Normal
Priority:  5 - Normal Item Group:  None
Status:  Fixed Assigned to:  None
Originator Name:  Originator Email:  -email is unavailable-
Open/Closed:  * Closed Release:  * 3.4.0
Operating System:  * GNU/Linux Fixed Release:  None
Planned Release:  None
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Thu 31 Mar 2011 04:29:12 PM UTC, comment #9: 
Rik <rik5>
Group administrator
Thu 31 Mar 2011 09:05:10 AM UTC, comment #8: 

Works for me, too.

Thanks!

Sebastian Hegler <shegler>
Thu 31 Mar 2011 05:55:34 AM UTC, comment #7: 

the fix from comment #6 works for me.
(Fedora 14 x86_64)

Michael Godfrey <godfrey>
Group Member
Thu 31 Mar 2011 05:39:01 AM UTC, comment #6: 

I believe I have a fix.  I'm attaching a new version of _quiver_.m.  Try replacing your existing version with this one.  It should go into a directory path like /usr/local/share/octave/3.4.0/m/plot/private/.  Please report back if this works.

(file #23062)

Rik <rik5>
Group administrator
Tue 22 Mar 2011 11:22:12 AM UTC, comment #5: 

Please see the new attachment for MATLAB's results.


Sebastian Hegler <shegler>
Mon 21 Mar 2011 09:23:40 PM UTC, comment #4: 

Okay, I think I've found the problem.  The scale factor for the length of the arrows is set to zero when only a single point in space is used (with potentially many vectors from said point).  Could you run the following in Matlab and post a picture of the results.  I need to fine tune the scaling parameters.


quiver3 ([5 5 5 6],[5 5 5 6],[5 5 5 6],[1 -1 -1 -1],[1 -1 1 -1],[1 -1 1 -1]);


Rik <rik5>
Group administrator
Mon 21 Mar 2011 09:30:23 AM UTC, comment #3: 

Okay, here's some sreen shots showing the issue, this time with another quiver3 command:


quiver3 ([5 5 5 ],[5 5 5],[5 5 5],[1 -1 -1 ],[1 -1 1 ],[1 -1 1])





Sebastian Hegler <shegler>
Fri 18 Mar 2011 07:56:50 PM UTC, comment #2: 

Sure, your example exactly marks the problem: If the initial point is identical, nothing is shown. This goes for as many points as you want, for whichever initial point you want.

MATLAB gives the one arrow with two heads that I mentioned.

Anonymous
Fri 18 Mar 2011 07:14:09 PM UTC, comment #1: 

Isn't the vector field supposed to be single-valued?  I think the problem is that you have specified two values for the vector to draw at the exact same point (0,0,0).  If you actually have two points then quiver3 seems to work.


quiver3 ([0 0],[0 0],[0 1],[1 -1],[1 -1],[1 -1])

or to get what you were intending
quiver3 ([0 0],[0 0],[0 1],[1 -1],[1 -1],[1 -1])
quiver3 (0,0,0,1,1,1);
hold on
quiver3 (0,0,0,-1,-1,-1);


How does Matlab handle this?  Does it accept multiple values for the same point?

Rik <rik5>
Group administrator
Fri 18 Mar 2011 03:46:29 PM UTC, original submission:  

Using the following command, I'd expect to see two arrow heads and a closed line between them:


quiver3 ([0 0],[0 0],[0 0],[1 -1],[1 -1],[1 -1])


But I see an empty 3D plot window. This is independent of the graphics backend used.

Anonymous

 

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Attach Files:
   
   
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Attached Files
file #23062:  __quiver__.m added by rik5 (13KiB - text/x-octave)
file #22986:  matlab2.png added by shegler (18KiB - image/png)
file #22976:  matlab.png added by shegler (20KiB - image/png)
file #22977:  octave3.4.0.png added by shegler (16KiB - image/png)

 

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  • -email is unavailable- added by godfrey (Posted a comment)
  • -email is unavailable- added by shegler (Updated the item)
  • -email is unavailable- added by rik5 (Posted a comment)
  • -email is unavailable- added by shegler
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    Follow 10 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2011-03-31 rik5 StatusReady For Test Fixed
        Open/ClosedOpen Closed
    2011-03-31 rik5 Attached File- Added _quiver_.m, #23062
        StatusConfirmed Ready For Test
    2011-03-22 shegler Attached File- Added matlab2.png, #22986
    2011-03-21 rik5 StatusNeed Info Confirmed
    2011-03-21 shegler Attached File- Added matlab.png, #22976
        Attached File- Added octave3.4.0.png, #22977
    2011-03-18 rik5 StatusNone Need Info
    2011-03-18 shegler Carbon-Copy- Added -email is unavailable-

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