Octave is avaliable for OS2006 although I didn't try it on maemo.
On "easy debian" (thank You quole) I installed Octave3.0 and looks like it works.
Worth mentioning - Octave itself is quite resource hungry application, starting it on my desktop at work WinXP@P4 3.0GHz takes about 11 seconds to get the final prompt so don't panic if You'll start it on NIT and forget about what You've done
For example
graphing step response like:
step(tf([1 2],[2 10 5]))
takes about 10secs on my P4.
On the tablet - it was I think more than a minute - but worked.