Im looking for a Reverse Polish Notation (RPN) calculator program for Linux. Must be programmable, im not too picky on the exact syntax of the language, as long as there is adequate instruction on its use (man page). Preferably something in the Ubuntu Repositories (or has a .deb for it). Any suggestions welcome!

Fedora has orpie. Never used it, but it's the only thing that comes up on a "yum search rpn". Description:
Edit: might be interesting to write your own, if you are so inclined.

You don't seem to require that it have a GUI, so sometimes the oldest is the best. It's called dc. It's beem part of the UNIX world longer than the C programming language has. These days, it's part of the bc package:

http://ftp.gnu.org/pub/gnu/bc/bc-1.06.tar.gz

It's so ancient and so classic that your distribution might already contain an executable for it. Try this at the command line:
Hope this helps.

dc is great, but I sure wish it had the basic transcendental functions. It integrates quite well with scripts.
Kevin Barry

Turns out i have dc already installed. Looked through the man pages and found a few things missing that i may require. Trigonometric functions being one of them. I will need to use exponents also. Possibly some basic matrices. Basically a fully functional engineering grade calculator. As far as the programming goes, i guess since it runs in the shell i would just need to write a script for automating arithmetic?

Edit: I also tried orpie, looks loaded with features, probably more than i need. Is it possible to write programs for it though?

I have actually written a basic command-line RPN calculator for fun in just about every language I learned!

As for GUI calculators, "Qalculate!" has a pretty good RPN mode.

I tried Qalculate, packed with features, quite impressive. Is it programmable?

I actually don't know what a programmable calculator is.

if you want there ARE the HP calc's for the desktop
http://freshmeat.net/projects/nonpareil/

i run a 11c on gnome

You might look at some of these:
http://www.hpcalc.org/hp48/pc/emulators/

Kevin Barry

WP-34S is possibly the best non-graphical calculator you can have.
See a picture of it here. An image tells more than a thousand words.

• You can run the WP-34S emulator in Linux, Windoze and MacOS.
  Simply download the emulator and run it, for free. Amazing!
  
• You can also buy the real thing and have it in your pocket
  You will receive an HP-30S modified with the WP-34S firmware.
  
• If you are adventurous, you can also make your own RPN calculator
  There are flash tools for Linux, Windoze and MacOS here].

Documentation:

• Beginner's Guide
• Owner's Manual
  This is an online version, for quick evaluation.
  When you download the emulator, it comes with documentation.

If you are using Emacs, GNU Calc, i.e. M-x calc RET.

frgomes
You do realize that this thread is from 2009 !!!
and it is 4 years old

also reported
everything is pointing to buying the hp product

Yes... despite the thread is very old this is [one of] the top hits Google delivers.
I've invested (or wasted?) a lot of time finding a good RPN calculator and I'd like to help people less lucky than me (or less stubborn than me) who failed to find this wonderful calculator.

No. The thread is not about buying a product. The thread is about downloading the emulator and running it on Linux, Windoze or MacOS.
I said you can also buy the product. I said you can also build a calculator yourself. These are informational statements.
These are additional options you have. I'm not pushing anyone to buy or build anything.
You are free to choose between running the emulator, buy the real thing or hacking with electronics.

-- Richard Gomes

There is an android app, Droid48sx. You can probably get the sources for that. It is a full HP-48/SX programmable.

Bonne chance,
~~~ 0;-Dan