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Full Version: Meltiple Equation Solver PRIME Vs. HP 50G
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I am so used to using the 50G it is a bit hard to get out of old habits when trying to use the HP PRIME.
I teach Physics,Astronomy.General Science and Oceanography Labs.
In one of my Physics Labs(Standing waves on a string) I used the HP50G E.W. to creates an equation to predict the mass that will create a number of standing waves(Segments) in a string.
mass = (4*mu*f^2*L^2)/g*n^2

When I try doing this on the Prime, I can enter the equation OK,but when I get a syntax error when I try to enter it.
I am using the solver APP.
Am I in the wrong Mode(symbolic/NUMERIC) for this to work?
Or could it be a problem with the names of the variables in the equation?

Quote:
I am so used to using the 50G it is a bit hard to get out of old habits when trying to use the HP PRIME.
I teach Physics,Astronomy.General Science and Oceanography Labs.
In one of my Physics Labs(Standing waves on a string) I used the HP50G E.W. to creates an equation to predict the mass that will create a number of standing waves(Segments) in a string.
mass = (4*mu*f^2*L^2)/g*n^2

When I try doing this on the Prime, I can enter the equation OK,but when I get a syntax error when I try to enter it.
I am using the solver APP.
Am I in the wrong Mode(symbolic/NUMERIC) for this to work?
Or could it be a problem with the names of the variables in the equation?


The variables must already exist (according to the Help screen, anyway). One way to address this is to use the built-in variables A through Z and "theta". To create a variable just do something like:

0 [shift][eex] mu

Then start the solver.

Quote:


The variables must already exist (according to the Help screen, anyway). One way to address this is to use the built-in variables A through Z and "theta". To create a variable just do something like:

0 [shift][eex] mu

Then start the solver.


I was using the example in the users guide and it says (I think) "In addition to the built-in variables, you can use one or more
variables you created yourself (either in Home view or in the
CAS" you do not have to use the "System" variables. Page 264 U.G.
I really do not understand about creating variables in this manner. When using the EqW on the HP50G I write the equation I am interested in store it in a variable and then use the Numerical Solver to use it.
It does not seem so straight forward on the PRIME.
I think I followed the directions correctly on page 264 but I get a syntax error.

Quote:

I was using the example in the users guide and it says (I think) "In addition to the built-in variables, you can use one or more
variables you created yourself (either in Home view or in the
CAS" you do not have to use the "System" variables. Page 264 U.G.
I really do not understand about creating variables in this manner. When using the EqW on the HP50G I write the equation I am interested in store it in a variable and then use the Numerical Solver to use it.
It does not seem so straight forward on the PRIME.
I think I followed the directions correctly on page 264 but I get a syntax error.


On the Prime, variables are created by storing something into their names. So for example, pressing [1][shift][eex][alpha][vars][alpha][eex] will store the number 1 into the variable AP and create the variable if it does not already exist. The manual is correct -- what it does not make clear is that the variables you wish to use the the solver must already have been created before you can use them with the solver. So if you are in the solver, exit the solver (go to the Home view) and press the appropriate key sequence similar to what I suggested to create your variables. Just store dummy values in them. Then re-start the solver and type your equation using the variable names you created. Page 424-425 will give you more information.

Ideally, the solver should just create the variable as needed, but I believe that is currently not implemented on the Prime. On the HP50G, non-existing variables are created as needed.

Edited: 7 Oct 2013, 4:57 p.m.

Hello Harold,

Im coming from a 50G as well**

mass = (4*mu*f^2*L^2)/g*n^2

I was able to enter user defined variables for: mass, mu, f, g and n then use these, plus the HOME Real variable L in Solver APP.

1. Home settings to Textbook or Algebraic. I dont think RPN mode allows user variables to be defined...

2. On Home screen, enter mass:=1 ENTER // stores mass as user variable

3. Repeat #2 for other variables. Note since L is uppercase, I think its already stored as a Home Real variable.

4. Go to Solve APP (symb) and key in the mass formula above. Vars / user / (mass, f, g...) can be selected or type in each term using ALPHA

5. Go to Solve APP (Num) and edit all the known terms which were probably set to 1.0. Press Solve for the term you want to solve for.

Best,
Carl

** Disclaimer - I'm about 48 hours ahead of you using the prime. Other real experts will help us both if needed :)

Edited: 7 Oct 2013, 5:16 p.m.

Quote:


On the Prime, variables are created by storing something into their names. So for example, pressing [1][shift][eex][alpha][vars][alpha][eex] will store the number 1 into the variable AP and create the variable if it does not already exist. The manual is correct -- what it does not make clear is that the variables you wish to use the the solver must already have been created before you can use them with the solver. So if you are in the solver, exit the solver (go to the Home view) and press the appropriate key sequence similar to what I suggested to create your variables. Just store dummy values in them. Then re-start the solver and type your equation using the variable names you created. Page 424-425 will give you more information.

Ideally, the solver should just create the variable as needed, but I believe that is currently not implemented on the Prime. On the HP50G, non-existing variables are created as needed.



Thanks, I think I have got the idea now. It seems that the Prime does things a lot differently than on the 50G. I guess I will finally get the hang of things,but it will take a while. It was also not helpful to try to this on the PRIME while I was working with three sections of students in General Science Lab today.
I just broke down and did in my old trusty 50G.
I will eventually get to work on the PRIME too.