HP Prime: CAS variable to Solver error message
05-31-2014, 03:47 PM
Post: #1
 CR Haeger Member Posts: 275 Joined: Dec 2013
HP Prime: CAS variable to Solver error message
Hello,

Prior to firmware update, this workaround allowed a CAS equation to be written, assigned to Solver.E1 then numerically solved for term(s):

F_A1:=fv=av*((1+rate)^per-1)/rate;
Solve.E1:='F_A1';

which would (1) load fv=av*((1+rate)^per-1)/rate into E1, (2) promt to create user variables (yes) then (3) allow for numerical solving.

------

Since firmware update, E1: shows Error: Syntax Error. It shows this until after steps (2) and (3) completed, then will start showing the formula.

This threw me off, thinking I had a non valid equation being sent to Solver. I hope this can be fixed, or perhaps suggest better workarounds for creating equations then solving using Solver App.
06-02-2014, 02:11 PM
Post: #2
 Tim Wessman Senior Member Posts: 2,089 Joined: Dec 2013
RE: HP Prime: CAS variable to Solver error message
I don't see any of this being possible with the previous version. What I see is the equation being stored into E1, but then I can't solve or anything with it.

Where are your fv,av etc defined at? Exact steps?

TW

Although I work for the HP calculator group, the views and opinions I post here are my own.
06-02-2014, 02:57 PM (This post was last modified: 06-02-2014 03:01 PM by CR Haeger.)
Post: #3
 CR Haeger Member Posts: 275 Joined: Dec 2013
RE: HP Prime: CAS variable to Solver error message
(06-02-2014 02:11 PM)Tim Wessman Wrote:  I don't see any of this being possible with the previous version. What I see is the equation being stored into E1, but then I can't solve or anything with it.

Where are your fv,av etc defined at? Exact steps?

In prior version (5443?) I could enter following in CAS:

F_A1:=fv=av*((1+rate)^per-1)/rate;
Solve.E1:='F_A1';

fv, av etc. are not defined at this point...

Then when I opened Solve App, I could click on E1** then Num. It would ask me if I wanted to create variables fv, av etc. and I click OK. From here, I could SOLVE for any variable.

** The only difference with new firmware is that E1 initially shows "Error: Syntax Error".
06-02-2014, 05:50 PM (This post was last modified: 06-02-2014 05:51 PM by Rich.)
Post: #4
 Rich Junior Member Posts: 47 Joined: Jan 2014
RE: HP Prime: CAS variable to Solver error message
Not sure if this is the same issue, but i would typically use this as a workaround, before the latest firmware update, to enter a formula in the Solver App:

In the CAS screen I can enter this:
E1:='a+b=c'

Then click on the Solver App and the system would ask if you wanted the variables to be created for each unknown variable, specifically the ones that are lower case.

This would result in a formula of
a+b=c

within the E1 variable within the solver app. Now when i do this same procedure, after the firmware update, i get:
Error: Syntax Error

in the E1 variable within the Solver App. When i click on Show, it does display the equation but i cannot use it. Clicking on the Num button i get No variable in equation, displayed.

So i have an exam on Thursday and i really need this function... Anyone know if they see an error with my steps or have another work around. I used this method extensively last semester and it appears not to work after i updated the firmware to 32.6030.
06-02-2014, 07:16 PM
Post: #5
 CR Haeger Member Posts: 275 Joined: Dec 2013
RE: HP Prime: CAS variable to Solver error message
(06-02-2014 05:50 PM)Rich Wrote:  Not sure if this is the same issue, but i would typically use this as a workaround, before the latest firmware update, to enter a formula in the Solver App:

In the CAS screen I can enter this:
E1:='a+b=c'

Then click on the Solver App and the system would ask if you wanted the variables to be created for each unknown variable, specifically the ones that are lower case.

This would result in a formula of
a+b=c

within the E1 variable within the solver app. Now when i do this same procedure, after the firmware update, i get:
Error: Syntax Error

in the E1 variable within the Solver App. When i click on Show, it does display the equation but i cannot use it. Clicking on the Num button i get No variable in equation, displayed.

So i have an exam on Thursday and i really need this function... Anyone know if they see an error with my steps or have another work around. I used this method extensively last semester and it appears not to work after i updated the firmware to 32.6030.

Rich - I think you and I are seeing the same issue, error message with the new firmware.

In your example however, make sure the check the E1 box before clicking NUM. This should take you to the Num screen and prompt for a,b,c as new variables - which then can be solved.

I tend to save the CAS formula as a variable before saving into Solve.E1. I do this as I usually want to do work on the formula in CAS - and I hate retyping it.

06-02-2014, 08:34 PM (This post was last modified: 06-02-2014 08:34 PM by Rich.)
Post: #6
 Rich Junior Member Posts: 47 Joined: Jan 2014
RE: HP Prime: CAS variable to Solver error message
Thank you, this works for me!

Checking the formula E1, then selecting the Num allows for the creation of the new variables.

I still initially get the Error: Syntax Error message, but it goes away once I:

Go into the Num screen, then press ESC, and finally back into the Solver App. E1 showing up as the formula as requested. If i go from Num to Symb i still get the error message.
06-02-2014, 08:50 PM
Post: #7
 CR Haeger Member Posts: 275 Joined: Dec 2013
RE: HP Prime: CAS variable to Solver error message
(06-02-2014 08:34 PM)Rich Wrote:  Thank you, this works for me!

Checking the formula E1, then selecting the Num allows for the creation of the new variables.

I still initially get the Error: Syntax Error message, but it goes away once I:

Go into the Num screen, then press ESC, and finally back into the Solver App. E1 showing up as the formula as requested. If i go from Num to Symb i still get the error message.

hmm... that may be a clue. E1 used to autocheckmark itself using the prior firmware. Perhaps since it saw a "valid" formula in E1 but sees an error now.
06-02-2014, 09:15 PM
Post: #8
 Tim Wessman Senior Member Posts: 2,089 Joined: Dec 2013
RE: HP Prime: CAS variable to Solver error message
Will investigate, thanks. There were some issues around the CAS/equation interaction that were resolved, and this (not checking it) I am guessing was a side effect of those.

TW

Although I work for the HP calculator group, the views and opinions I post here are my own.
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