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DuxDucisH · 05-04-2019, 12:42 PM

Hello, i recently got an HP prime which i found lovely to use. However, i've had some issues that i have no idea of solving. Searching haven't helped and im getting more and more frustrated.

I'll start of with my biggest issue right now. When differentiating equations, i seem to be unable to get an symbolic answer, instead the calculator seems to use the assigned value for the variable in question, and if it doesn't have a value it just uses "0" and gives a numerical answer to that.

Does anybody have an idea what im doing wrong? I'll Attach a screenshot so you can see what i mean. Doesn't seem to make any difference if i use the diff command or the derivate template. Ive tried using both small and large Xs but it doesnt make any difference.

Han · 05-04-2019, 03:30 PM

(05-04-2019 12:42 PM)DuxDucisH Wrote: Hello, i recently got an HP prime which i found lovely to use. However, i've had some issues that i have no idea of solving. Searching haven't helped and im getting more and more frustrated.

I'll start of with my biggest issue right now. When differentiating equations, i seem to be unable to get an symbolic answer, instead the calculator seems to use the assigned value for the variable in question, and if it doesn't have a value it just uses "0" and gives a numerical answer to that.

Does anybody have an idea what im doing wrong? I'll Attach a screenshot so you can see what i mean. Doesn't seem to make any difference if i use the diff command or the derivate template. Ive tried using both small and large Xs but it doesnt make any difference.

(The following assumes CAS mode, as seen in your screenshot.)

The variable X (upper case) is a system variable and always has a value stored in it, similar to the TI-83 or TI-84 series of calculators. Normally, one would delete a variable (to make it symbolic) and all would be as expected. However, system variables are built-in and cannot be deleted. So use the lower case x for your expressions. If you still get numerical values then it is likely that the lower case variable x has a value stored in it. You can delete the variable (to make it symbolic) via: purge(x).

DuxDucisH · 05-08-2019, 08:05 AM

Thanks, but it didn't work. Not sure what i'm doing wrong

Aries · 05-08-2019, 11:16 AM

Try a soft reset (ON+Symb or using the Reset hole at the back) or ESC+Apps+ON Wink

Best,

Aries Smile

roadrunner · (This post was last modified: 05-08-2019 12:43 PM by roadrunner.)

Make sure x isn't defined as global in a program, or defined as a user variable:

-road

edited to correct syntax

Han · 05-08-2019, 02:13 PM

(05-08-2019 08:05 AM)DuxDucisH Wrote: Thanks, but it didn't work. Not sure what i'm doing wrong

Your screenshot shows that the variable x still contains a numerical value (i.e. it is not symbolic). As others have pointed out, even though x is not a defined as a CAS variable, it seems to be defined elsewhere (either via an app or program). Either remove those instances, or use a different variable that is not defined.

chromos · 05-08-2019, 02:26 PM

Isn't somewhat confusing when you purge(x)<ENTER> with info "No such variable x" and then you type x<ENTER> with 353.24 as result?

roadrunner · 05-08-2019, 03:24 PM

It's only confusing the first time Smile

-road

ijabbott · 05-08-2019, 04:09 PM

How to delete a user variable:

https://www.hpmuseum.org/cgi-sys/cgiwrap...ead=254251

Tim Wessman · 05-08-2019, 04:16 PM

As explained "x" is defined somewhere and being pulled in. Look at the user variable menu as shown, and if you find an "x" there, press delete on it.

If it is defined in a program or an application by an inconsiderate programmer, you'll need to find which it is.

Else just use x1 or so on till you do.

Han · 05-08-2019, 04:23 PM

(05-08-2019 02:26 PM)chromos Wrote: Isn't somewhat confusing when you purge(x)<ENTER> with info "No such variable x" and then you type x<ENTER> with 353.24 as result?

It's due to the fact that the purge command is specifically for CAS variables (variables created within the CAS view). Here's a short list of the types of variables you might have:

https://hpmuseum.org/forum/thread-215.html

chromos · 05-08-2019, 08:18 PM

Thank you all for reply to my (rhetorical?) question. I know about different variable types and how it works, but:

If you're working in CAS environment and one command (purge) is interpreting your x differently than other commands then it doesn't seem too logical. :-)

Aries · 05-09-2019, 07:06 AM

If "soft" reset and/or clearing the memory don't work, I suggest re-flashing the O.S. to the latest version Wink

Best,

Aries Smile

Tim Wessman · (This post was last modified: 05-09-2019 07:57 AM by Tim Wessman.)

(05-09-2019 07:06 AM)Aries Wrote: If "soft" reset and/or clearing the memory don't work, I suggest re-flashing the O.S. to the latest version
Best,

Aries

You are not helping here with things like this...

The user has an x variable defined. Full Stop. Either the user defined it, or installed a program that installed it.

Aries · 05-09-2019, 10:55 AM

Oh … I was just helping, sorry if I was wrong Sad

All the best,

Aries Smile

Zaphod · 05-09-2019, 11:30 AM

(05-09-2019 10:55 AM)Aries Wrote: Oh … I was just helping, sorry if I was wrong
All the best,

Aries

I think it was a good suggestion regardless of this particular problem already being identified.

Aries · 05-09-2019, 07:00 PM

(05-09-2019 11:30 AM)Zaphod Wrote:
(05-09-2019 10:55 AM)Aries Wrote: Oh … I was just helping, sorry if I was wrong
All the best,

Aries

I think it was a good suggestion regardless of this particular problem already being identified.

Thanks mate Wink

Best,

Aries Smile