I thought Octave will be a valuable skill when I enter the industry but I could not have been more wrong. Does anyone still use Octave? Is it worth learning?
What tools or languages would you recommend as alternatives to someone graduating from university today?
Also, while perhaps this example is overplayed, Andrew Ng's hugely successful coursera nanodegree on Machine Learning is taught on octave. Andrew Ng explains the reasons for this beautifully in his course, and I agree.
As for "I thought it would be a valuable skill; I could not have been more wrong", it depends. To remove the obvious comment, there is octave, matlab, and octave/matlab. Matlab is still 100% huge in the industry, and getting into this path through octave is at least equivalent, if not better (given you also have to learn more under-the-hood concepts than you might have to in matlab).
However, I will assume here that you are referring specifically to the whole "investing in the octave ecosystem on top of already knowing the matlab language" issue. I would argue that octave tends to be more used in teaching and academia, so you're partly right. But at the same time, I would argue that as an open source project, the opportunities for participation and the transferable skills you can get from that are extremely relevant in any resume.
I personally recommend Python (using NumPy, SciPy, MatPlotLib/Seaborn, Pandas, Keras/PyTorch, Gensim, etc). There’s a lot more that you’ll need to bolt together yourself, but there are packages for pretty much anything you’ll likely need to do in terms of math/science/analysis/ML.
That’s not to say that you shouldn’t advocate for Octave, though! I haven’t used it other than to poke around, but it seems like a great package.
If your skill with Octave makes you more effective in a role, then it's still valuable even if your employer doesn't specifically require experience with it.
I started using Octave after a coworker showed me how he used Matlab as a DSP prototype workbench. At the time I couldn't justify asking the boss for my own Matlab subscription, so I applied what I learned using Octave instead. At this point in my career, Matlab is available to me but Octave does what I need.