HP Forum Archive 18

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Using equation solver multiple times on HP35s.. Message #1 Posted by ravwalia on 7 Feb 2008, 5:10 p.m. Hello All, I recently bought a HP35s and finding it a good tool, especially the equation solver. Let's say I have a equation R=(A-B)/(A+B). To use the equation solver I do EQN -> Solve R Then I go and run the solver. Now when the equation finishes, if I want to re-run the solver for the exact same equation, is there a shortcut or do I have to do EQN -> Solve R again? Thanks, Rav.

Re: Using equation solver multiple times on HP35s.. Message #2 Posted by designnut on 7 Feb 2008, 7:05 p.m., in response to message #1 by ravwalia See section 6 in your instructions, you can write and keeep all the equations you wish. Sam

Re: Using equation solver multiple times on HP35s.. Message #3 Posted by Chuck on 7 Feb 2008, 8:59 p.m., in response to message #1 by ravwalia You are correct: to solve the same equation a second time you need to enter the EQN list for your desired equation; right-shift SOLVE; and your variable. I don't know of a short-cut to begin the process all over again. CHUCK

Re: Using equation solver multiple times on HP35s.. Message #4 Posted by designnut on 8 Feb 2008, 2:28 a.m., in response to message #3 by Chuck I didn't know that you could use equations within a program, they complete actions easier than if you had programmed the individual actions as program steps. I entered and rearranged RECT<>POLAR programs By Jeff O and called subroutines. It was good initial practice in getting a kinesthetic sense of where keys were located and getting hands on practice and learning to find and correct mistakes, what worked and what didn't. I recommend it. His original program is: http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv017.cgi?read=122519#122519 Considering the complexity of possible programs and the state of the instructions I think we must learn from each other. When the original 35 came out I suggested we rewrite formulas into keystroke sequences, I think it increasingly important to move from the pencil and paper era to take advantage of the calculator capabilities. E Samuuel Levy RET EE

Re: Using equation solver multiple times on HP35s.. Message #5 Posted by ravwalia on 8 Feb 2008, 11:44 a.m., in response to message #4 by designnut Hello Guys, So it doesn't look like you can invoke the solve once and then use it again. For clarification. The equation R=(A-B)/(A+B) is for calculating the reflection coefficient from the load impedance and the reference impedance. The nice thing about the HP35s is that the above equation can handle the variables being complex numbers. Sometimes I would like to have a bunch of impedances that I need to work out the reflection coefficients for, so I use the HP35s and the equation above. Just a little annoying have to go Eqn r-> solve R each time.

Re: Using equation solver multiple times on HP35s.. Message #6 Posted by Martin Pinckney on 8 Feb 2008, 11:54 a.m., in response to message #5 by ravwalia Quote: So it doesn't look like you can invoke the solve once and then use it again. That's one of the reasons I lost interest in the 35s, because the solver is essential to my calculator use. My 27s and 17b make it very easy to do repeat solves. Even with the lowly 22s it is easier to do this than with the 35s.

Re: Using equation solver multiple times on HP35s.. Message #7 Posted by Jeff Kearns on 8 Feb 2008, 12:42 p.m., in response to message #6 by Martin Pinckney Guys, Another option is to simply write a program for this equation, and set FN equal to whatever the label of the program is. You can use SOLVE (VAR) repeatedly thereafter. Jeff Kearns

Re: Using equation solver multiple times on HP35s.. Message #8 Posted by designnut on 8 Feb 2008, 7:00 p.m., in response to message #7 by Jeff Kearns You may type any equation you want, as many as you want using EQN. You may use cursors to scroll through equations to the one you want. Anytime that equation is shown you can use SOLVE_ to solve for whatever variable you want. Key the desired variable, and it will prompt you for the missing values. If you have them stored it shows that value, if correct R/S, otherwise key in the correction. You can change a number to Imaginary by keying i X, then you may add the real part. The equation may not be an expression, it must have an equals sign. If you wish to disuse your 35S let me know. Sam

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