SageMath is a free open-source mathematics software system licensed under the GPL. It builds on top of many existing open-source packages: NumPy, SciPy, matplotlib, Sympy, Maxima, GAP, FLINT, R and many more. Access their combined power through a common, Python-based language or directly via interfaces or wrappers.

Mission: Creating a viable free open source alternative to Magma, Maple, Mathematica and Matlab.

This package contains documentation in French.

Note that the package for English documentation (sagemath-doc-en) contains far more documentation than any of the other languages. So if you're finding this package lacking in content, then you could try that one as well.