Giac is a Computer Algebra System made by Bernard Parisse. It provides
features from the C/C++ libraries PARI, NTL (arithmetic), GSL (numerics),
GMP (big integers), MPFR (bigfloats) and also
- Efficient algorithms for multivariate polynomial operations
(product, GCD, factorization, groebner bases),
- Symbolic computations: solver, simplifications, limits/series, integration,
- Linear algebra with numerical or symbolic coefficients.
- Partial Maple and TI compatibility.
- It has interfaces in texmacs and sagemath.

It consists of:
- a C++ library (libgiac)
- a command line interpreter (icas/giac)
- an FLTK-based GUI (xcas) with interactive geometry and
formal spreadsheets.