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
>>
>>
>
>