Reverse Polish Notation

Overheal

no results in search? What kind of nerds are yeh!

So I wanted to know more about this RPN thing. My old man looked at me funny for needing a TI-83 for my pre-calculus class and suggested an HP/RPN calculator to me but he didn't explain it all that well. I dont see the advantage but he swears by them.

IS there an advantage to RPN that merits using one or learning to use one?

bnt

The first electronic calculator (HP 35) used RPN: it's conceptually similar to the way a CPU works. The main thing about RPN is the Stack, which takes the place of brackets. The calculator has no sense of algebraic order either: you have to take care of that yourself by pushing numbers on to the stack and/or rearranging calculation steps. So it's a bit more mental work, but fewer keystrokes.
Example: to evaluate 5 x 8^(-3) the keys are:
5 ENTER
8 ENTER
3 +/- y^x
X

The ENTER key pushes the number on to the stack, and operations pull them back off.

I got a HP 35s last year. I think it's superior to the old style scientific calculators at least; though more modern ones, such as Casios with "Natural Textbook Display", can be easier to use (I think). The HP 35s does have an Algebraic mode too, so you can switch over if you like.

But it's not legal for university exams, since it's programmable, so I have a Casio FX-991ES for that. Do you need a TI-83? I've just been through four years of Engineering at university with the Casio.


PS: you don't need to buy hardware to try RPN yourself. There are free calculators out there, including Free42 (HP 42s emulator) and Xcalc.

Overheal

I got an ipod app for RPN. Yeah I basically need the Ti-83 because it's the standard in the system over here. I could surely try to use my classic casio in class but I'd rather not stir up ****.

Already trying to get back into quadratic formulas by using the Ti-83 - not my favorite device by any means. Handles very differently to the Casio. I miss it. But I don't want to regress if it's going to hurt me later on when I need to use the graphing functions and during exams


Speaking of quadratics, they never taught us the Complete The Square method in the LC. Made my head explode for about an hour but it actually seems very reliable.

Michael Collins

Overheal wrote: »

...Speaking of quadratics, they never taught us the Complete The Square method in the LC. Made my head explode for about an hour but it actually seems very reliable.

I think this is/was done at Junior Cert level to prove the Quadratic Formula. I certainly did it back then and I'd be very surprised if it still isn't done. Particularly given how important the quadratic formula is, and how often it's used from then on.

Overheal

Michael Collins wrote: »

I think this is/was done at Junior Cert level to prove the Quadratic Formula. I certainly did it back then and I'd be very surprised if it still isn't done. Particularly given how important the quadratic formula is, and how often it's used from then on.

In my school anyway they avoided it. I figure because it usually results in fractions, which are then squared. Then theres square rooting of fractions involved.

I do find it handy though. I wish they had taught it to me all the way up.

LeixlipRed

It's definitely on the course. It has come up the very odd time in computing integrals which have inverse trignometric functions as their answers.

bnt

There are some people who will not let go of their RPN calculators. The HP 12C Financial calculator from 1981 was such a hit with bankers and brokers that HP kept making it well in to the 90s, and they've just released a new "Limited Edition" version. 100x as fast as the original, which is not much of a feat after 30 years, I suppose ... :cool:

The HP 15C is the Scientific model in that family, and you can download an emulated version of it, here.