lispdoc - results for abs

(abs number)
Function: Return the absolute value of the number.
(defun diff (num)
  "Return the function that finds the difference from num."
  #'(lambda (x) (abs (- x num))))
Mentioned in:
CLtL2 - 12.5.2. Trigonometric and Related Functions
CLtL2 - 12.5.3. Branch Cuts, Principal Values, and Boundary Conditions in the Complex Plane
HyperSpec - Function ABS
Successful Lisp - chapter05