Using Octave instead of Matlab in control engineering
I've finished my masters degree in electrical engineering one month ago and throughout my entire studies, i only used octave instead of matlab. I also had some control systems classes, which can be perfectly done with the control toolbox for octave (it is not built in). However, as you mentioned, octave has nothing like simulink, so if you need something like that, you don't really have a choice. For the matlab part and the usual undergraduate control systems classes, octave should be perfectly fine!