I have only used some of the modules that are available for SymPy. Most of them are not complete enough to use professionally, but I try to spend some time to l

I have only used some of the modules that are available for SymPy. Most of them are not complete enough to use professionally, but I try to spend some time to learn them since I would prefer to use them when they get more complete -- but that's one reason why they are inferior. At one point I was using SymPy and I wanted to invert a symbolic matrix, a rather small one but it had some off-diagonal elements. This took a few seconds in mathematica, after a few hours in SymPy I had to halt the execution of that line. I never got around to look at the code to see what caused it, probably some simple bug, but that's another reason. I have used Sage somewhat as well. It has more features than SymPy, for what I do professionally. Still some features are missing that I would need. But this might also just be a problem of the amount of experience I have with these tools. The last problem is that these are much slower than mathematica. I would certainly not say that I'm a good programmer, so my code is probably very slow and badly written. In mathematica I have done some calculations that take days to complete, but they were quite heavy calculations. For these projects I could in principal have used SymPy, I know it has enough features, but with how much slower it is, it would be useless (unless I was able to improve my code to compensate). With more experience I could give more specific concerns.