The Museum of HP Calculators

HP Forum Archive 21

[ Return to Index | Top of Index ]

Solving with the built-in equations of the 35s
Message #1 Posted by Palmer O. Hanson, Jr. on 15 Oct 2012, 9:25 p.m.

Page 7-6 of the 35s manual describes use of the built-in equations from the keyboard. I would like to use the "2x2 lin solve" equation in a program. How do I do that?

      
Re: Solving with the built-in equations of the 35s
Message #2 Posted by gene wright on 16 Oct 2012, 8:05 a.m.,
in response to message #1 by Palmer O. Hanson, Jr.

This should show how. Good to finally meet you a few weeks ago in Nashville!

Learning Module

            
Re: Solving with the built-in equations of the 35s
Message #3 Posted by gene wright on 16 Oct 2012, 9:24 p.m.,
in response to message #2 by gene wright

Ah, I mis-read your original question.

You cannot use one of the built-in equations in a user program. Sorry!

      
Re: Solving with the built-in equations of the 35s
Message #4 Posted by Andrew Feist on 16 Oct 2012, 9:02 p.m.,
in response to message #1 by Palmer O. Hanson, Jr.

I don't think you do--I think you can only type your own equations into a program, not use the ones that are built in.

            
Re: Solving with the built-in equations of the 35s
Message #5 Posted by Dieter on 17 Oct 2012, 3:17 p.m.,
in response to message #4 by Andrew Feist

You cannot use equations from the 35s equation list in your own programs. But solving a 2x2 system is so trivial that it can be done in a very short user routine:

RCL A
RCL* F
RCL D
RCL* C
 -
RCL A
RCL* E
RCL B
RCL* D
 -
 /
ENTER
RCL* B
+/-
RCL+ C
RCL/ A
This returns the two unknowns in X and Y.

Actually you can also do this in just two lines, using the EQN-feature:

([A,D]*[F,-C])/([A,B]*[E,-D]>G)
([C,B]*[E,-F])/G
Type "STO G" to enter ">G". Please also note that the minuses are unary (signs, not operators). This solution also works for A=0. ;-)

Dieter

Edited: 17 Oct 2012, 3:28 p.m.


[ Return to Index | Top of Index ]

Go back to the main exhibit hall