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How to find "inverses?" - Printable Version

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How to find "inverses?" - PhysicsNerd - 11-26-2007

How do you find inverses? (the one where you swap x and y and solve for y) I've looked through the manual and it says to press the button 1/x but isn't that only the reciprocal?

Re: How to find "inverses?" - Vieira, Luiz C. (Brazil) - 11-26-2007


just want to help, and would like to know:

1 - which calculator are you using?

2 - can you give us an example of what do you want to compute?

The second question of mine is mainly to understand what do you mean by swap x and y and solve for y.


Luiz (Brazil)

Re: How to find "inverses?" - PhysicsNerd - 11-26-2007

Oh, my bad; I'm using an hp50g. I would like to graph the inverse of x^2 or abs(x).

I would also like to find the inverse of sec (x), with x being any real number within the domain of sec.

I just want to find the inverse of a function like:


the inverse would be g(x)= +/- sqrt(x)

Edited: 26 Nov 2007, 12:26 a.m.

Re: How to find "inverses?" - Tim Wessman - 11-26-2007

Make a little program like this. If I am understanding correctly, that is how I did it back in high school. It won't work for some functions though.



Re: How to find "inverses?" - PhysicsNerd - 11-28-2007

Are you telling me that the hp50g doesn't have a built-in button for finding inverses? Unfortunately, I don't know how to program. =/

Re: How to find "inverses?" - Walter B - 11-28-2007

Fortunately, this is an opportunity for you to start learning ;)

Re: How to find "inverses?" - Ed Look - 11-28-2007

What calculator does??

I agree, you'll have to write the program yourself. And just start with the manual just to get your feet wet; then try to obtain a copy of the HP 48G Advanced User's Reference guide. It should be still available in book form from Calcpro.com for about thirty bucks or so.

I believe also it's available on Eric Reichlin's HP48 site in the download section electronically as a .pdf file.

This manual is very worthwhile. I was able to use it to get myself to a point at which I can begin to believe I can program almost anything, given reasonable time and maybe a few days more, on a HP-48G series or 49G series machine, which does include the HP-50g. One caveat: I did learn to program back in high school and college, even if that was back just shortly after stone tablets got obsolete, HP programmable scientific calculators and a "real" computer language.

But if as you say you don't know how to program, then I would strongly recommend you start with the 50g manual, then get that AUR I mentioned in this message.

Edited: 28 Nov 2007, 10:20 a.m.

Save your time. PhysicsNerd has refused to read the manuals for 6 months - Allen - 11-28-2007

Ed, Walter, Tim:
Great advice! The program is elegant and short, and the suggestion to read the manuals is the best advice you could give in this situation. Unfortunately our Nerd has received the same suggestion in nearly every thread (s)he has started, and has repeatedly proven incapable or unwilling to engage in even the smallest amount of self-study. (to include typing a short program someone else wrote to directly answer the above question!).

For reference to this hilarity see threads:
HELP! My 50g is giving answers in Fractions! (includes comments for all May 2007 Discussions encouraging Nerd to read the excellent and freely available manuals),

Graphing Functions,

Simple 50g questions.

Re: Save your time. PhysicsNerd has refused to read the manuals for 6 months - Giancarlo (Italy) - 11-28-2007

Hi Allen.

The program is elegant and short

...so elegant and short that I've just typed and saved it both into the emulator and into the real thing!

Thanks to the contributors.

Best regards.


Re: Save your time. PhysicsNerd has refused to read the manuals for 6 months - Chris Dean - 11-28-2007

I think PhysicsNerd is just trying to wind up well intentioned respondents to his questions.

Edited: 28 Nov 2007, 1:18 p.m.

This is a classic answer - Artur-Brazil - 11-28-2007

Congratulations, Luiz

What a solution!!!!

Cheers, Artur