Function: sign (<expr>) Attempts to determine the sign of <expr> on the basis of the facts in the current data base. It returns one of the following answers:
pz (positive or zero),
nz (negative or zero),
pn (positive or negative), or
pnz (positive, negative, or zero, i.e. nothing known).
There are also some inexact matches for
?? sign to see them.
(%o1) true (%i2)