Function: abs
Section: transcendental
C-Name: gabs
Prototype: Gp
Help: abs(x): absolute value (or modulus) of x
Description: 
 (small):small	labs($1)
 (int):int	mpabs($1)
 (real):real	mpabs($1)
 (mp):mp	mpabs($1)
 (gen):gen:prec	gabs($1, prec)

