Re: Axis layout of xyz in 3D plotting

Tee Nor plots are obviously done with gnuplot (x11 terminal). perhaps it is
an issue with a very old gnuplot version (3.x.x)?
I cannot reproduce the problem with neither 5.2.4 nor 5.4.2.

Dmitri.


On Mon, Aug 23, 2021 at 12:05 PM Markus Mützel <[email protected]>
wrote:

> I don't have a function `gui_mode`. But if I comment out those two lines,
> I see two figures as shown in the attached screenshot.
> Figure 4 looks right-handed to me. Figure 5 (the one with the interchanged
> labels) has axes labels that make it appear left-handed.
>
> What does the function `gui_mode` do? Maybe it reverses some axes
> directions?
>
> ISTR I saw something similar in the past with buggy graphics drivers. Do
> you see the same if you start Octave with `LIBGL_ALWAYS_SOFTWARE=1 octave
> --gui`?
>
> *Gesendet:* Montag, 23. August 2021 um 17:41 Uhr
> *Von:* "Tee Nor" <[email protected]>
> *An:* "Markus Mützel" <[email protected]>
> *Cc:* [email protected]
> *Betreff:* Re: Axis layout of xyz in 3D plotting
> Hello again Markus,
>  No problems,
> Please note the ijk unit vectors are not displayed. This is a special
> reminder just for me (quick hack job).
> Here are the two plotting  example.oct script shown in the last figures.
> I'm still building Debian 10.9.0  Octave 6.3.0 ... Debian 10 is at 4.4.1-5.
> I built Octave 5.2.0 on Debian 7.7.0, works just fine, been using it ever
> since for advanced development.
> Using Debian 7.11.0 with Octave 3.6.2 native version with distribution,
> as this is my baseline development platform. As stated before, I am please
> with
> Octave, my usage has been engineering graphical plotting/documentation of
> ngspice,
> mathematical and electromagnetics and served me very well for
> instructional purposes.
> I thank you again for your time and interest.
>
> Regards, T
>
> On Mon, Aug 23, 2021 at 10:41 AM Markus Mützel <[email protected]>
> wrote:
>
>>
>> Sorry, I probably was ambiguous:
>> Please, show some self-contained code with which Octave produces a plot
>> with left-handed coordinate system for you.
>>
>> Markus
>>
>> *Gesendet:* Montag, 23. August 2021 um 16:35 Uhr
>> *Von:* "Tee Nor" <[email protected]>
>> *An:* "Markus Mützel" <[email protected]>
>> *Cc:* [email protected]
>> *Betreff:* Re: Axis layout of xyz in 3D plotting
>> Hello agian Markus,
>> I am pleased you have taken interest.
>> I have included an example of "undergraduate cross product textbook
>> confusion".
>> First you will see the mathematical  (used in theatrical
>> Electromagnetics) illustration
>> common to cross product vector analysis.
>> Second is illustrations of simple changing the axis label to seemling
>> correct this issue,
>> By the way, this is not earth shattering news, I discovered this in
>> Mathworks during the 90's.
>> Please Be Careful not to be fooled by my trickery of Octave, it's for
>> illustration only,
>> There is nothing incorrect with Octave's workings. More of a wish list.
>>
>> Please note this is a simple single vector from 0,0,0 to 1,2,1 in all
>> cases.
>> In figure 4, this looks as seen Fig 188 (b). Here the orientation is
>> view(145,-218) as
>> also the plot code (t,x,y,z) for the vector. However, if rotated back
>> around, so that
>> it looks like Fig 188 (a), x axis and y axis move where y is left and x
>> is right of the plot.
>> Thus, Figure 5, I simple changed the xlabel and ylabel statements, and
>> all is well,
>> except x data is y data, and y data is x data. Completely incorrect, as
>> shown.
>> So no matter where this plot is viewed from, it is still a Left handed
>> coordinate system.
>>
>> This is a very small detail, however, It's used during exam's to "weed
>> out bell curve" types.
>> I looked into changing this, and will take much time to introduce a
>> switch to change
>> between left and right coordinate systems.
>>
>> Please indicate any more missing information, I take a lot for granted in
>> electromagnetics.
>>
>> Regards, T
>>
>>
>> On Mon, Aug 23, 2021 at 8:09 AM Markus Mützel <[email protected]>
>> wrote:
>>
>>> Please, keep the mailing list in CC.
>>>
>>> Octave's plotting system uses a right-handed coordinate system.
>>> If you'd like to switch to a left handed coordinate system, reverse one
>>> of the axes.
>>>
>>> Can you give an example where Octave uses a left-handed coordinate
>>> system when plotting for you?
>>>
>>> Markus
>>>
>>>
>>> *Gesendet:* Montag, 23. August 2021 um 13:27 Uhr
>>> *Von:* "Tee Nor" <[email protected]>
>>> *An:* "Markus Mützel" <[email protected]>
>>> *Betreff:* Re: Axis layout of xyz in 3D plotting
>>> Hello Markus,
>>>   Thank you very much for the help. I installed Octave 6.3.0 on Vista,
>>> Apparently, On Debian 10.9.0 I'll have to re-build Octave 6.3.0 as
>>> Debian 10 Octave version is 4.4.1.  This issue has not changed between
>>> versions.
>>> Please examine the included attachment:
>>> MathWorks (MathLab) and Octave are using the "Left-hand" coordinate
>>> system,
>>> so it is not currently possible to change to the "Right handed" system.
>>> In either case, the plots are correct as seen per the xyz numbers.
>>> As indicated by the preferred statement, while developing textbooks etc,
>>> the solution was to just leave out the axis information, avoiding
>>> confusion.
>>> In my last note, the location (1,1,1) of ijk in both (a) and (b) are the
>>> same,
>>> just flip (b) over, except x and y are swapped. Also, gui_mode() is now
>>> considered an error in MS world. I do not plan to use MS.
>>> Suggest adding a setup switch between right and left hand option.
>>> Regards, T
>>>
>>>
>>> On Sat, Aug 21, 2021 at 4:09 PM Markus Mützel <[email protected]>
>>> wrote:
>>>
>>>> Am 21. August 2021 um 08:52 Uhr schrieb "Tee Nor":
>>>> > Has anyone noticed,
>>>> > Most math and physics textbooks have the positive axis arrowheads
>>>> direction layout as follows:
>>>> >      x axis arrow pointing down and to the left,
>>>> >      y axis arrow pointing to the right,
>>>> >      z axis arrow pointing to the top.
>>>> > Using GNU Octave version 3.6.2,
>>>> > Please show how to make my positive axis look this way.
>>>> > My view always looks like x and y are swapped.
>>>> > Regards, T
>>>>
>>>> Octave 3.6.2 is ancient and I don't have access to it to test in that
>>>> version.
>>>> In version 6.3.0, the following command seems to rotate the axes in the
>>>> way you describe:
>>>>   view ([100, 30]);
>>>>
>>>> HTH,
>>>> Markus
>>>>
>>>>
>>>
>>>
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