;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;                                                          ;;;;;;;;
;;;;;;  All files in this directory or any subdirectories are   ;;;;;;;;
;;;;;;  copyright 1997, 1998, 1999, 2000, 2002.                 ;;;;;;;;
;;;;;;  by Rafael D. Sorkin.  All rights reserved.              ;;;;;;;;
;;;;;;                                                          ;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun ! (n) "Factorial of INTEGER argument"
  (cond 
   ((not (integerp n)) (error "This one is for integers only"))
   ((< n 0) Infinity%)
   ((= 0 n) 1)
   (t (* n (! (1- n))))))

  ; Since `!' is built into some TCL implementations, we don't define it in
  ; bib.gen.tcl (It seems not to be present in CLtL1, cmucl or gcl, but Clisp
  ; definitely does have it.)


(defun product-m (X) " Multiplies together numbers in a list"
   (apply (function *) X))

(defalias 'product 'product-m)

(defun sum-m (X) "Adds up the numbers in a list" (apply (function +) X))
  
(defalias 'sum 'sum-m)