Pari/GP is a computer algebra system with a compact syntax and features ranging from basic numerics up to sophisticated number theory. (Pari is the library of C code, GP is the interpreter.)

Emacs things related to Pari/GP include

PariEmacs was included with Pari/GP in the past but is now separate. It has help display using gphelp and a help browser. gp.el is another interactive mode using ComintMode. Some function names clash between PariEmacs and gp.el so can’t be used together.