Xcas is an interface to perform computer algebra, function graphs, interactive geometry (2-d and 3-d), spreadsheet and statistics, programmation. It may be used as a replacement for high end graphic calculators for example on netbooks (for about the same price as a calculator but with much more performances). Giac/Xcas has a compatibility mode for people used to the Maple or Mupad CAS as well as for users of TI calculators (TI89, Voyage 200, TI Nspire CAS)