CAS seems to Be in Auto Simplify Mode
06-09-2022, 04:08 PM
Post: #1
 tim_crouse Junior Member Posts: 12 Joined: Jun 2022
CAS seems to Be in Auto Simplify Mode
When in CAS mode

If I enter 3x-17=22

Then hit enter

Then place () parenthesis and go copy the equation such that I have

(3x-17=22) Then add +17 >> (3x-17=22)+17

I get 3x=w39 as it is in CAS mode I am expecting 3x-17+17=39

I am running the latest OS. Does CAS mode simplify on the fly whenever possible in v2.1.1.4603?

Thanks
-Tim C.
06-09-2022, 04:20 PM
Post: #2
 tim_crouse Junior Member Posts: 12 Joined: Jun 2022
RE: CAS seems to Be in Auto Simplify Mode
See the attachment for a better overview

Attached File(s) Thumbnail(s)

06-09-2022, 06:08 PM (This post was last modified: 06-09-2022 06:13 PM by C.Ret.)
Post: #3
 C.Ret Member Posts: 262 Joined: Dec 2013
RE: CAS seems to Be in Auto Simplify Mode
(06-09-2022 04:08 PM)tim_crouse Wrote:  I get 3x=w39 as it is in CAS mode I am expecting 3x-17+17=39

Check your settings in the Shift CAS Setting page; your preference corresponds to Simplify: None.

(06-09-2022 04:08 PM)tim_crouse Wrote:  Then place () parenthesis and go copy the equation such that I have (3x-17=22)

Make it easy, enter your expression (or equation) and simply press + 1 7 ENTER.
The HP Prime will do all the copy-paste for you using the powerfull local Ans function.

You may also enter ans directly ( Shift + key). Note that default Ans is Ans(1). And furthermore Ans(2) , Ans(3), ... etc are references to the older answers store in the displayed queue.
06-10-2022, 01:46 PM
Post: #4
 tim_crouse Junior Member Posts: 12 Joined: Jun 2022
RE: CAS seems to Be in Auto Simplify Mode

I apologize for the length of the following question

Could you provide some insight into the xTheta key? In general I have a hard time getting solve to work in CAS mode. Folks mention it is because the equations are numeric and not symbolic.

I ask these questions because when I try to experiment I get syntax errors so some guidance would be helpful. . .

I know I will have a syntax error or some error when the exTheta produces an "a" or "A" but when it provides a variable in the form of "x" it always seems to work.

To add more confusion to my mind on the subject I see multiple ways to invoke the solve operation:

OPTION 1
-Set up HOME >> APP >> SOLVE
-hit esc to exit to command-line mode "Solve" is in the title bar.

Do I then hit the toolbox key and select either CAS Solve or App Solve or do I simply enter an equation?

xTheta provides "A" in this mode

OPTION 2
-Set Up HOME >> APP >> FUNCTION >> ESC
xTheta provides "X" in this mode

-Tap CAS, CAS and FUNCTION displayed in title bar
xTheta provides "x" in this mode, I believe to be because CAS requires lower case VARs
-TOOLBOX >> CAS TAB >> SOLVE

OPTION 3
-Set Up >> HOME >> APP >> FUNCTION
TOOLBOX >> APP >> SOLVE >> SOLVE
Solve.SOLVE()
xTheta provides "X" in this mode

OPTION 4
-Set Up >> HOME >> APP >> FUNCTION
TOOLBOX >> CAS >> SOLVE >> SOLVE
CAS.Solve()
xTheta provides "X" in this mode
I am thinking this is prone to syntax errors as the is "X" and not "x" as I think this
is a CAS setup that a lower case VAR is required.

There are so many solve modes for basic equations that I get lost in which one I should use.

(and I haven't even covered the use of solver apps which I think should be straightforward as they are dedicated to a specific type of solve operation, Eg Triangle or Finance . . .

I guess what I am asking is how do I know when solve will work without a syntax error
and does it truly make a diff what xTheta provides? I understand the concept that xTheta provides the VAR based on the current mode the calculator is in.

Some of my frustration is that I am transferring from a TI NSpire CAS which adjusts the calculation mode automatically between numeric and symbolic resulting in fewer syntax errors (for me that is).

Any advice you could offer would be appreciated.

I have asked this question previously and the answer is that CAS is for symbolic and non-CAS is for numeric. My understanding of this is:

Use numeric when you want an exact answer, Eg x = -1

Use CAS when you expect an approximation or an equation as an answer:
x=2/3 or x= x-4

Is there a setting to have the Prime go into an auto mode when it comes to selecting the calculation mode it uses?