HP48GX User Guide Cover Plot

[DM48]

Does anyone have the equation that is displayed on the screen of the HP48G(X) user guide? I would like to plot it and can't find any reference to it.

[BruceH]

In the absence of other replies I'll chip in my 2p.

I don't think it is an equation plot - at least not in the sense of using one of the built-in tools to graph it. It looks to me more like a graphic generated by a program and so your question becomes: hows does the program generate that 'graph'?

There are probably several ways to do it. One would be to generate a matrix of a uniform 2d grid and then distort the grid by multiplying by matrices. (Folding the grid up into a U shape first; then wrapping the result around the outside of a 'wheel' would seem to be a good start.)

[Dave Frederickson]

It looks like a saddle surface.
https://en.wikipedia.org/wiki/Saddle_poi...le_surface

z = x^2 - y^2

[nlj]

(12-04-2021 01:52 AM)DM48 Wrote:  Does anyone have the equation that is displayed on the screen of the HP48G(X) user guide? I would like to plot it and can't find any reference to it.

Is it a rotated view of the wireframe plot in the example on Page 23-30? (I'm looking at the HP 48G Series User's Guide, Edition 8.) In that case, it is z = x^3 y - x y^3. But perhaps the one on the cover is not as convoluted as that one is.

[DM48]

I just found this.

“The HP 48GX advanced scientific graphing calculator displays a wireframe plot of the surface z = x3y - xy3.”

https://www.hpl.hp.com/hpjournal/94aug/covaug94.htm

[DM48]

(12-07-2021 02:34 AM)nlj Wrote:  

(12-04-2021 01:52 AM)DM48 Wrote:  Does anyone have the equation that is displayed on the screen of the HP48G(X) user guide? I would like to plot it and can't find any reference to it.

Is it a rotated view of the wireframe plot in the example on Page 23-30? (I'm looking at the HP 48G Series User's Guide, Edition 8.) In that case, it is z = x^3 y - x y^3. But perhaps the one on the cover is not as convoluted as that one is.

I think you nailed it. I’m going to try and graph it and see what happens.

[DM48]

Plotted. I just need to determine how to rotate it if possible. Any ideas?

Photo here: https://imgur.com/a/Bm2uugB

[nlj]

(12-07-2021 12:18 PM)DM48 Wrote:  Plotted. I just need to determine how to rotate it if possible. Any ideas?

Maybe something like:

EQ: Z = Y^2 - X^2
XE: -1.4
YE: -2
ZE: -0.6
Step Indep: 14 Depnd: 10

and a window of -1 to 1 for X, Y, and Z.

It looks quite close but I have a nagging suspicion that it is inside out and an optical illusion flips it in the mind's eye from front to back!

   

In comparison to the one on the cover of the manual:

   

[JoJo1973]

(12-07-2021 12:18 PM)DM48 Wrote:  Plotted. I just need to determine how to rotate it if possible. Any ideas?

Photo here: https://imgur.com/a/Bm2uugB

Let the 48GX be your TEACHer: within its trove of treasures for EXAMPLE, in an unintended twist of PLOT you'll be able to use a WIRE and catch the knowledge you desire! ))

[DM48]

(12-07-2021 04:30 PM)nlj Wrote:  

(12-07-2021 12:18 PM)DM48 Wrote:  Plotted. I just need to determine how to rotate it if possible. Any ideas?

Maybe something like:

EQ: Z = Y^2 - X^2
XE: -1.4
YE: -2
ZE: -0.6
Step Indep: 14 Depnd: 10

and a window of -1 to 1 for X, Y, and Z.

It looks quite close but I have a nagging suspicion that it is inside out and an optical illusion flips it in the mind's eye from front to back!



In comparison to the one on the cover of the manual:

Thank you. I was able to reproduce your results using YOUR equation. Many thanks. It's close to the user guide, but not quite the same perspective. I will work on it.

I am going to continue to look at the equation that seems to be the one HP is convinced they used, but I am not so sure it is. Interesting issue!