- Engineers (like electrical etc) use Matlab

- Statisticians use R

- Rich people sometimes use Mathematica

- People with some CS background use Python/numpy/sklearn

For "purer" math, like symbolic differentiation and such, I don't really know any of those people, but I think Mathematica has a lot in that area. The others have stuff, but less developed. But pretty much every major language has linear algebra at this point.