In 2012, Corbin Champion made Octave 3.6 available on Android, so using Terminal Emulator you can run many Octave commands using actual Octave code.
You will need to install at least three apps to enable Octave with plotting. You can install additional toolboxes if you want them.
The three apps you need are:
- Octave Main Package
- Octave Gnuplot Package
Consider donating as well to support his work.