Some years ago I used MuPAD as a free computer algebra system. However since 2005 it's not free anymore. So, are there any good free or even better open-source computer algebra systems for linux coming close to commercial products like mathematica or maple?
I have using Cantor http://edu.kde.org/applications/all/cantor/ for mathematical models
Note that there are several pages.
In addition to the already mentioned Maxima, another visible option is Axiom. However, my impression is that Maxima's mindshare and userbase is greater than Axiom. However, I don't think either of these have functionality comparable to Mathematica or Maple. On the other hand, Mathematica at least is quite actively developed, and continues to improve.