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# HP Prime using user variables with rpn set as input method

06-10-2014 12:19 AM

I have just yesterday purchased HP Prime after 30 years of using a number of hp scientific calculators.

I have never had any problems using any of the previous models.

The Prime does not seem to allow me to create a user variable an assign a value to it in a sensible manner.

I can do it by creating a user variable which is automatically assigned the value of 0.

Then I have to use the shift mem function and edit the user variable from there.... A VERY POOR AND INEFFICIENT METHOD.

The prime will do it from cas but I did not buy this calculator for any other reason than I want to use rpn always.

I have downloaded both versions of the users manual and instructions for creating user variables do not work on my prime in rpn or in cas.

I updated software version to 2014 3 31 (6030)

Hardware version A

CAS Version 1.1.0-46

Can anyone help please?

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## HP Prime using user variables with rpn set as input method

06-10-2014 09:18 AM

I have only a little experience with Primes RPN.

It does seem that for user variable, you do need to first create them before storing anything to them. **a ENTER OK** creates user variable a and puts a 0 on stack 1:

**123 ENTER**,** 'a' ENTER**, **Shift Sto>** *or* **123**_**'a'**_**Shift Sto>** ( _ = space key) store 123 in a and put 123 on stack 1:

Other more expert users may offer better advice.

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## HP Prime using user variables with rpn set as input method

06-11-2014 02:04 PM

You don't need to use the Memory Manager to edit variables' values in RPN.

Example of *creating* a *new* variable with 12.34 stored in it:

MYVAR Enter

12.34 Enter

Shift ( ) <-- puts single-quote marks around your var; very important!

Vars User 2 (press number next to your variable) Enter

Shift EEX (Sto)

Example of *changing* its value to 56.78:

56.78 Enter

Shift ( )

Vars User 2 (press number next to your variable) Enter

Shift EEX (Sto)

Instead of using the Vars key, you can also type out its name in ALPHA mode; that's faster for vars with very short names.

Just be sure to put your var's name in single quote marks when you don't want it to be evaluated.

All of the above assumes that you're talking about variables that you create, not the permanently built-in variables which you can use right away without creating them.

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## HP Prime using user variables with rpn set as input method

06-11-2014 04:25 PM

@Joe_Horn wrote:You don't need to use the Memory Manager to edit variables' values in RPN.

Example of

creatinganewvariable with 12.34 stored in it:MYVAR Enter

12.34 Enter

Shift ( ) <-- puts single-quote marks around your var; very important!

Vars User 2 (press number next to your variable) Enter

Shift EEX (Sto)

Example of

changingits value to 56.78:56.78 Enter

Shift ( )

Vars User 2 (press number next to your variable) Enter

Shift EEX (Sto)

Instead of using the Vars key, you can also type out its name in ALPHA mode; that's faster for vars with very short names.

Just be sure to put your var's name in single quote marks when you don't want it to be evaluated.

All of the above assumes that you're talking about variables that you create, not the permanently built-in variables which you can use right away without creating them.

Thanks for your intelligent reply Joe, but it doesn't work on my Prime.

When I enter 'MYVAR' as you suggest it appears on the stack as M*Y*V*A*R .

This is totally useless for me.

It is actually an expression for the product of the built in vars M, Y, V, A, and R.

I am very disappointed with this calculator.

To say that it is a Reverse Polish Notation calculator is grossly misleading. Most complicated functions just don't work in RPN mode.

Tony

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## HP Prime using user variables with rpn set as input method

06-11-2014 05:44 PM - edited 06-11-2014 05:47 PM

If MYVAR does not exist, then you create it by typing MYVAR ** without quote marks.** It looks like you were quoting it; that causes it to be pased as 'M*Y*V*A*R'.

Once the variable is created, quote it to store into it, and omit the quotes to evaluate it.

Hope that helps!

P.S. You wrote, "Most complicated functions just don't work in RPN mode." If you give examples, we might be able to help you. Otherwise all I can do is commiserate. 😉

Disclaimer: I do not work for HP; I'm just a happy HP calculator addict.

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## HP Prime using user variables with rpn set as input method

06-12-2014 03:32 AM

@Joe_Horn wrote:If MYVAR does not exist, then you create it by typing MYVAR

It looks like you were quoting it; that causes it to be pased as 'M*Y*V*A*R'.without quote marks.

Once the variable is created, quote it to store into it, and omit the quotes to evaluate it.

Hope that helps!

P.S. You wrote, "Most complicated functions just don't work in RPN mode." If you give examples, we might be able to help you. Otherwise all I can do is commiserate. 😉

Disclaimer: I do not work for HP; I'm just a happy HP calculator addict.

Thanks Joe,

The advice re variables is vey good. I have got that sorted thanks to you.

Here are 2 examples of where function don't work in RPN mode.

COEFF(x^2-2) enter

results in

Do you want to create a variable called COEFF

PROOT([1,0,-2]) enter

results in

ERROR: Syntax Error

These are just 2 of the many functions that I have tried to use in the last couple of days that have not worked in RPN mode.

I admit that I have become very frustrated and may come across as a little Jaded.

I have also lost track of all the function failures I have had and have just kept trying to find something that works in RPN mode and henc made a sweeping statement that Mmost functions don't work in RPN mode.

This is probably a little irrational but I have yet to find a more tham simple function that works in RPN.

Thanks

Tony

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## HP Prime using user variables with rpn set as input method

06-12-2014 05:58 AM - edited 06-12-2014 06:00 AM

Tony wrote:

> Here are 2 examples of where function don't work in RPN mode.

> COEFF(x^2-2) enter

> PROOT([1,0,-2]) enter

You chose RPN mode, so use Reverse Polish Notation, not algebraic notation. For example, instead of SIN(.5), you must put .5 on the stack and then execute SIN. No parentheses, except to specify the number of arguments to take from the stack when the function can take a variable number of arguments.

Therefore, your examples are done this way in RPN:

First example:

x Enter (this creates variable x if it doesn't already exist)

'x' Enter

[x^2]

2 [-]

coeff(1) Enter (notice that coeff must be spelled in lowercase letters!)

--> [-2], answer.

Second example:

[ 1, 0, -2 ] Enter

proot(1) Enter

--> [-1.414, 1.414], answer.

So in RPN, put the arguments on the stack, then execute the function (just like you've always done in RPN on previous models). What's different about Prime from previous models, however, is that some functions do not always take the same number of arguments from the stack. For those functions, specify the desired number of arguments in parentheses after the function name. For example, to find the maximum number in stackl levels 1 through 7, use max(7).

Hope that helps!