Is 3D graphing still on HP's Prime to-do list?

[DrD]

Well, to answer that kind of question, it's the starting point of your foray into the Xcas camp, for which Google, or the like, is your best guide. Xcas is the mother of the Prime CAS, and the father, (Parisse), often fills in missing details (here) when we stumble along the CAS path...

This is yet another one of those hang time on the learning curve details...

-Dale-

[Joe Horn]

(09-12-2015 05:59 PM)Parmenedes Wrote:  So why would the CAS use lowercase variables at all?

Good news and bad news.

The Good News: There is a good reason, actually. CAS is able to perform symbolic math, to answer questions like "What are the binomial factors of 15x^2-2x-24?" This obviously requires the use of undefined variables, that is, variables to which no value has been assigned. The Advanced Graphing app, however, is not intended for symbolic math at all, but rather for creating a visual approximation of real-number approximations. This obviously requires the assigning of real values to real variables.

So CAS has to use undefined variables to perform symbolic math, and graphing has to use real variables with real values in them.

It was decided by the Prime design team to address this dichotomy by building in 27 permanently defined real variables (A-Z and θ) and using them for graphing, and then letting CAS use anything undefined (including lowercase letters, but not limited to that) when undefined variables are needed.

The Bad News: This results in the experience you described (we've all experienced it), namely, we use CAS to perform some nifty symbolic math (using undefined lowercase variables of course, because the uppercase variables always have values in them so they can't be used for symbolic math), then tried to graph the result... only to get an error because the grapher wants real variables (because it has to store reals in them).

It's annoying. Having an understandable reason only makes it slightly less annoying.

(09-12-2015 05:59 PM)Parmenedes Wrote:  It seems like it would be better to have the Prime be consistent across the whole system.

It can't be consistent, for the reason explained above. However, IMHO the unfortunate result of this dichotomy (that CAS results can't be directly graphed without manually editing the variables) should be addressed by the design team.

Brainstorm from Captain Obvious: Wouldn't it be cool if the graphing apps automatically converted all lowercase x's and y's to uppercase X's and Y's? Can anybody foresee any problems that such automatic conversion might cause? It would solve this problem of using CAS results in the graphing apps.

[primer]

(09-12-2015 10:55 PM)Joe Horn Wrote:  Brainstorm from Captain Obvious: Wouldn't it be cool if the graphing apps automatically converted all lowercase x's and y's to uppercase X's and Y's? Can anybody foresee any problems that such automatic conversion might cause? It would solve this problem of using CAS results in the graphing apps.

Ho yes, it would be very nice that once you selected a formula from CAS environment, the calc propose you to map variables.
It could list all variables found from your formula on a screen and allow you to choose which one will be X, Y, T ...
most of time, only one variable (x) would be found and mapping to X preset.

That would make the link between CAS and graph tools easy and flexible.

it's just my feeling (my dream).
Best Regards,

[Han]

(09-12-2015 10:55 PM)Joe Horn Wrote:  Brainstorm from Captain Obvious: Wouldn't it be cool if the graphing apps automatically converted all lowercase x's and y's to uppercase X's and Y's? Can anybody foresee any problems that such automatic conversion might cause? It would solve this problem of using CAS results in the graphing apps.

If I am not mistaken, you can already do this... sorta. For example, in CAS one can simply do something like:

V1(x,y):= <here, copy and paste the formula in lower case x y>

and the formula will be auto"magically" converted to V1(X,Y). Copy/pasting is pretty easy to do on the HP Prime. Pressing [Symb] will show V1 with the formula properly converted.

[parisse]

I would say that the culprit of upper/lowercase variables is the hp38g, with all these preassigned variables with type corresponding to name. Now perhaps it is possible to convert on the fly undefined lowercase variables to uppercase variables in Home and (non-geometry) Apps.

[primer]

(09-13-2015 12:16 AM)Han Wrote:  If I am not mistaken, you can already do this... sorta. For example, in CAS one can simply do something like:

V1(x,y):= <here, copy and paste the formula in lower case x y>

and the formula will be auto"magically" converted to V1(X,Y). Copy/pasting is pretty easy to do on the HP Prime. Pressing [Symb] will show V1 with the formula properly converted.

Ideed, that's a nice workaround.
By the way, when you copy/paste in CAS, take care it may broke your formula. see here issue when copying previous result. BTW, issue also occurs when "getting from CAS" with Menu key.
Regards,

[Parmenedes]

I'm genuinely curious. I figure there must be some reason that HP made it that way, even if it doesn't makes sense to me.

[John Colvin]

The way the Prime handles variables and the separate RPN and CAS environments is a major downside to using the Prime, an otherwise extremely powerful and versatile calculator. If the 50G can can do symbolic math using the same variables and plot the results without converting from lower to upper case, it seems that it wouldn't be impossible for the prime to do the same. Maybe in a future firmware upgrade.