HP Prime Solver Variables Issue



#2

I'm trying to solve the following equation in the solver application:

To/T=1+(γ-1)/2*M^2

I previously created the following variables: "To", "γ" ("T" and "M" are already built in the calculator from factory)

If I input values for "T", "γ" and "M" and try to solve for "To", I get the following message:

"Constant? The value of the equation is the same at every point sampled."


I noticed that, If I replace "To" for a different variable, say "P", the solver obtains the correct answer.

What am I doing wrong?

Please help!


#3

Hello,

how did you create a variable called γ ?

cyrille


#4

This is a lowercase Greek gamma character (it looks more like a lowercase letter 'y'). Its easily entered into the Prime using the Shift-9 helper popup.

#5

Anibal,

I looks like the Solver doesn't like the 'To' variable. Perhaps its because 'To' is also a reserved word--I don't know.

If you instead use 'T0' (Tee-Zero) the solver works correctly.

It looks like another one for the bug list.


#6

It seems that the HP Prime interprets “To” as the programming command “TO”. I tried "end" and "eNd" as substitutes of "To" in my original equation, then I hit the solve button and...

Constant!

IMHO, if we are not supposed to use the Prime Program Language commands and operators, then HP Prime should not even allow you to create the variable and if you attempt to, it should display a warning message explaining that the particular character combination is reserved for system usage.

I'm missing my HP 48GX already!


#7

Quote:
It seems that the HP Prime interprets “To” as the programming command “TO”. I tried "end" and "eNd" as substitutes of "To" in my original equation, then I hit the solve button and...

Constant!

IMHO, if we are not supposed to use the Prime Program Language commands and operators, then HP Prime should not even allow you to create the variable and if you attempt to, it should display a warning message explaining that the particular character combination is reserved for system usage.

I'm missing my HP 48GX already!


Or at least until this is fixed(If ever) a list of system only variables should be shown in the users guide or an Advanced Users Guide ( If it is ever written).

#8

Quote:
... a list of system only variables should be shown in the users guide or an Advanced Users Guide ( If it is ever written).

Meanwhile, I threw together the following alphabetized list of Prime's reserved variables just for you. I hope it's complete. If not, let me know and I'll add what's missing:

http://holyjoe.net/hp/PrimeVars.htm

-Joe-

Edited: 19 Oct 2013, 8:23 a.m.


#9

Quote:

Meanwhile, I threw together the following alphabetized list of Prime's reserved variables just for you. I hope it's complete. If not, let me know and I'll add what's missing:

http://holyjoe.net/hp/PrimeVars.htm

-Joe-


Thank You. I think there may be other stuff, probably not variables, like PI that are forbidden as variable names and can not be assigned a value because they are constants and already have a value.

#10

Quote:

Thank You. I think there may be other stuff, probably not variables, like PI that are forbidden as variable names and can not be assigned a value because they are constants and already have a value.


I forgot one way to check this is to declare the suspect name as a variable and then write a equation and assign the values of the other variables in the equation in NUMERIC SOLVER so that the returned value of the suspect variable is not what you thought it would be,
For example:When I wrote an equation for the volume of a cylinder and used PI as a variable name, I chose values for the radius and height of 1and got the volume of 3.14*****. This meant that PI could not be used as a variable name.( I originally assigned a value of 1 to PI)
This method,or maybe a better one, could be used to root out other forbidden variable names/constants.

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