giac for Debian
  ---------------
  
  Note that there is a "debianold" directory in upstream tree, different
  from this one [1].  "Giac" is separately packaged for Quantian, a
  mathematical oriented Knoppix-derivated distribution [2], under
  different conditions (e.g. Pari support requires a patch to Pari
  sources if NTL not installed, in that case copy rules.no.pari to rules
  to build, in case NTL is installed you can safely copy rules.pari to
  rules); Quantian's Giac is built by configuring
  a series of advanced options in libraries it depends on (this package
  will use these options when they are set by default in the
  corresponding Debian packages).
  
  The command line interface can be started by typing "giac" or
  "icas".  Help is available thru the commands "aide", "cas_help",
  "en_cas_help", "fr_cas_help" and "es_cas_help" (choose language).
  "Giac" can be used as a C++ library.  Just install "libgiac0-dev".
  
  The GUI command are "xcas" and "xcasnew".
  
  [1] The corresponding package can be found at 
      ftp://ftp-fourier.ujf-grenoble.fr/xcas/
  
  [2] Visit http://dirk.eddelbuettel.com/quantian.html