GNU Octave - Lemmy

I would classify this as a matlab alternative. Plot stuff. Do Matrix calculations with direct (syntax) support in the programming language.

Now that is a name I have not heard in a long time. Mostly due to the decline in Matlab.
yeah; python and numpy won the wars I guess.
It’s easy to win a war when your enemy is strangling themselves to death.
Used it for an ML MOOC a long time ago. Switched to Python/Numpy for better general programming features. Numpy has pretty syntax for matrix computation, IMO.
Personally, I’d rather use Python with matplotlib when I need to plot stuff, but Octave is great if you have to deal with Matlab code!
SageMath is my go to for heavy math.
SageMath Mathematical Software System - Sage

SageMath is a free and open-source mathematical software system.

SageMath Mathematical Software System
Matlab is also awful about licensing. I took a Matlab class in college and we used gnu octave instead of the real thing. Works just as good, it’s just slightly different syntax.
GNU Octave is great when reviving old Matlab projects! I only wish for something similar to Simulink

See also maxima.sourceforge.io

This was my go to software for experimenting with linear algebra etc. Haven’t had the need recently though.

Maxima, a Computer Algebra System

Maxima is a fairly complete computer algebra system written in Lisp with an emphasis on symbolic computation. It is based on DOE-MACSYMA and licensed under the GPL free software license. Its abilities include symbolic integration, 3D plotting and solving differential equations.

Its good for legacy MATLAB projects. Use Python for new projects.