#xyzzy の epsilon 周りがおかしい

gistfile1.cl

;; xyzzy の epsilon 周りがおかしい
;;
;; http://twitter.com/TwilightClover/status/26251344464
;; http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_short-_tive-epsilon.html

(dolist (sym '((double-float-epsilon t)
               (double-float-negative-epsilon nil)
               (long-float-epsilon t)
               (long-float-negative-epsilon nil)
               (short-float-epsilon t)
               (short-float-negative-epsilon nil)
               (single-float-epsilon t)
               (single-float-negative-epsilon nil)))
  (let ((epsilon (symbol-value (car sym)))
        (positive (cadr sym)))
    (format t "~30S = ~@30S, test = ~S~%"
            (car sym)
            epsilon
            (if positive
                (not (= (float 1 epsilon) (+ (float 1 epsilon) epsilon)))
              (not (= (float 1 epsilon) (- (float 1 epsilon) epsilon)))))
    ))

gistfile2.txt

;; xyzzy 0.2.2.235
double-float-epsilon           = 2.220446049250313d-16          (test = t)
double-float-negative-epsilon  = 1.110223024625157d-16          (test = t)
long-float-epsilon             = 2.220446049250313d-16          (test = t)
long-float-negative-epsilon    = 1.110223024625157d-16          (test = t)
short-float-epsilon            = 2.220446e-16                   (test = nil)
short-float-negative-epsilon   = 1.110223e-16                   (test = nil)
single-float-epsilon           = 2.220446e-16                   (test = nil)
single-float-negative-epsilon  = 1.110223e-16                   (test = nil)
nil

gistfile3.txt

;; SBCL 1.0.37

DOUBLE-FLOAT-EPSILON           = 1.1102230246251568d-16         (test = T)
DOUBLE-FLOAT-NEGATIVE-EPSILON  = 5.551115123125784d-17          (test = T)
LONG-FLOAT-EPSILON             = 1.1102230246251568d-16         (test = T)
LONG-FLOAT-NEGATIVE-EPSILON    = 5.551115123125784d-17          (test = T)
SHORT-FLOAT-EPSILON            = 5.960465e-8                    (test = T)
SHORT-FLOAT-NEGATIVE-EPSILON   = 2.9802326e-8                   (test = T)
SINGLE-FLOAT-EPSILON           = 5.960465e-8                    (test = T)
SINGLE-FLOAT-NEGATIVE-EPSILON  = 2.9802326e-8                   (test = T)

gistfile4.txt

;; CLISP 2.48

DOUBLE-FLOAT-EPSILON           = 1.1102230246251568d-16         (test = T)
DOUBLE-FLOAT-NEGATIVE-EPSILON  = 5.551115123125784d-17          (test = T)
LONG-FLOAT-EPSILON             = 5.4210108624275221706L-20      (test = T)
LONG-FLOAT-NEGATIVE-EPSILON    = 2.7105054312137610853L-20      (test = T)
SHORT-FLOAT-EPSILON            = 7.6295s-6                      (test = T)
SHORT-FLOAT-NEGATIVE-EPSILON   = 3.81476s-6                     (test = T)
SINGLE-FLOAT-EPSILON           = 5.960465E-8                    (test = T)
SINGLE-FLOAT-NEGATIVE-EPSILON  = 2.9802326E-8                   (test = T)
NIL