fuzzy.lsp
 Version 1.00  31 October 2004
 Author Steven Jones

 Contact jones57@swbell.net include the word "nyquist" in subject line  

 The contents of this file are released under the terms of the GNU General
 Public License. See the file LICENSE.txt

 Fuzzy comparisons.

var

 Default fuzzy comparison threshold.

function

 (z= a b [e])
 Fuzzy equality test. Return true iff a and b are approximately the same
 value.

 a       - Flonum. Argument value.
 b       - Flonum. Argument value.
 e       - Flonum. Epsilon value, Default fuzzy:*epsilon* = 0.01
 return  - Bool. True iff |a-b| < e

;; fuzzy.lsp
;; Version 1.00  31 October 2004
;; Author Steven Jones
;;
;; Contact jones57@swbell.net include the word "nyquist" in subject line  
;;
;; The contents of this file are released under the terms of the GNU General
;; Public License. See the file LICENSE.txt
;;
;; Fuzzy comparisons.
;;

(provide 'fuzzy)
(current-file "fuzzy")

;; @doc var fuzzy:*epsilon*
;; Default fuzzy comparison threshold.
;;

(setq fuzzy:*epsilon* 0.01)


;; @doc function z=
;; (z= a b [e])
;; Fuzzy equality test. Return true iff a and b are approximately the same
;; value.
;;
;; a       - Flonum. Argument value.
;; b       - Flonum. Argument value.
;; e       - Flonum. Epsilon value, Default fuzzy:*epsilon* = 0.01
;; return  - Bool. True iff |a-b| < e
;;

(defun z= (a b &optional (epsilon fuzzy:*epsilon*))
  (plusp (- epsilon (abs (- a b)))))