Major Section: ACL2-BUILT-INS
(Signum x) is
x is negative,
The guard for
signum requires its argument to be rational (real, in
Signum is a Common Lisp function. See any Common Lisp
documentation for more information.
From ``Common Lisp the Language'' page 206, we see a definition of
signum in terms of
abs. As explained elsewhere
(see abs), the guard for
abs requires its argument to be a
rational (real, in ACL2(r)) number; hence, we make the same
To see the ACL2 definition of this function, see pf.