giac is an advanced symbolic and numeric calculator. The console interface is named icas or equivalently giac. The corresponding GUI program is called xcas.
These programs have extensive documentation. The GIAC/XCAS manual is available in Info format by invoking `info giac`, and in HTML and DVI format in /usr/share/giac/doc. One can also obtain some help about a keyword like this, from inside the program:
0>> ?gcd
Returns the greatest common divisor of 2 polynomials of several variables
or of 2 integers or of 2 rationals.
(Intg(a) or Poly),(Intg(b) or Poly)
gcd(45,75); gcd(15/7,50/9); gcd(x^2-2*x+1,x^3-1); gcd(t^2-2*t+1,t^2+t-2);
gcd((x^2-1)*(y^2-1)*z^2,x^3*y^3*z+(-(y^3))*z+x^3*z-z)
lcm,euler,modgcd,ezgcd,psrgcd,heugcd,Gcd
The equivalent output may be retrieved by invoking (e.g.) `cas_help gcd`.
This manual page was written by Carleos Artime <carleos@pinon.ccu.uniovi.es> and Ximin Luo <infinity0@debian.org> for the Debian GNU/Linux system (but may be used by others).