The Museum of HP Calculators

HP Forum Archive 21

 HP Prime Solver Variables IssueMessage #1 Posted by Anibal Morones Ruelas on 16 Oct 2013, 7:21 p.m. 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!

 Re: HP Prime Solver Variables IssueMessage #2 Posted by cyrille de Brébisson on 17 Oct 2013, 2:54 p.m.,in response to message #1 by Anibal Morones Ruelas Hello, how did you create a variable called γ ? cyrille

 Re: HP Prime Solver Variables IssueMessage #3 Posted by Mark Hardman on 17 Oct 2013, 3:05 p.m.,in response to message #2 by cyrille de Brébisson 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.

 Re: HP Prime Solver Variables IssueMessage #4 Posted by Mark Hardman on 17 Oct 2013, 3:43 p.m.,in response to message #1 by Anibal Morones Ruelas 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.

 Re: HP Prime Solver Variables IssueMessage #5 Posted by Anibal Morones Ruelas on 17 Oct 2013, 11:04 p.m.,in response to message #4 by Mark Hardman 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!

 Re: HP Prime Solver Variables IssueMessage #6 Posted by Harold A Climer on 18 Oct 2013, 9:24 a.m.,in response to message #5 by Anibal Morones Ruelas 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).

 Re: HP Prime Solver Variables IssueMessage #7 Posted by Joe Horn on 19 Oct 2013, 7:31 a.m.,in response to message #6 by Harold A Climer 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: -Joe- Edited: 19 Oct 2013, 8:23 a.m.

 Re: HP Prime Solver Variables IssueMessage #8 Posted by Harold A Climer on 19 Oct 2013, 9:31 a.m.,in response to message #7 by Joe Horn 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: -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.

 Re: HP Prime Solver Variables IssueMessage #9 Posted by Harold A Climer on 19 Oct 2013, 9:45 a.m.,in response to message #8 by Harold A Climer 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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