X-Git-Url: http://git.kpe.io/?p=kmrcl.git;a=blobdiff_plain;f=math.lisp;h=fcbab3c4baa2e922b0eba049af0bd04079a19739;hp=682cd74027776f7dfc5a3d4346c7a0ab2be55f50;hb=5470e786c59285e2f09497598505654672be847d;hpb=4a5b626f01db51b02f969adb33ddad6aa9ee303a

diff --git a/math.lisp b/math.lisp
index 682cd74..fcbab3c 100644
--- a/math.lisp
+++ b/math.lisp
@@ -7,7 +7,7 @@
 ;;;; Programmer:    Kevin M. Rosenberg
 ;;;; Date Started:  Nov 2002
 ;;;;
-;;;; $Id: math.lisp,v 1.4 2003/06/06 21:59:29 kevin Exp $
+;;;; $Id$
 ;;;;
 ;;;; This file, part of KMRCL, is Copyright (c) 2002 by Kevin M. Rosenberg
 ;;;;
@@ -34,3 +34,65 @@
   `(if (stringp ,obj)
       (parse-integer ,obj)
      ,obj))
+
+(defun histogram (v n-bins &key min max)
+  (declare (fixnum n-bins))
+  (when (listp v)
+    (setq v (coerce v 'vector)))
+  (when (zerop (length v))
+    (return-from histogram (values nil nil nil)) )
+  (let ((n (length v))
+	(bins (make-array n-bins :element-type 'integer :initial-element 0))
+	found-min found-max)
+    (declare (fixnum n))
+    (unless (and min max)
+      (setq found-min (aref v 0)
+	    found-max (aref v 0))
+      (loop for i fixnum from 1 to (1- n)
+	  do
+	    (let ((x (aref v i)))
+	      (cond
+	       ((> x found-max)
+		(setq found-max x))
+	       ((< x found-min)
+		(setq found-min x)))))
+      (unless min
+	(setq min found-min))
+      (unless max
+	(setq max found-max)))
+    (let ((width (/ (- max min) n-bins)))
+      (setq width (+ width (* double-float-epsilon width)))
+      (dotimes (i n)
+	(let ((bin (nth-value 0 (truncate (- (aref v i) min) width))))
+	  (declare (fixnum bin))
+	  (when (and (not (minusp bin))
+		     (< bin n-bins))
+	    (incf (aref bins bin))))))
+    (values bins min max)))
+	      
+
+(defun fixnum-width ()
+  (nth-value 0 (truncate (+ (/ (log (1+ most-positive-fixnum)) (log 2)) .5))))
+
+(defun scaled-epsilon (float &optional (operation '+))
+  "Return the smallest number that would return a value different from
+  FLOAT if OPERATION were applied to FLOAT and this number.  OPERATION
+  should be either + or -, and defauls to +."
+  (multiple-value-bind (significand exponent)
+      (decode-float float)
+    (multiple-value-bind (1.0-significand 1.0-exponent)
+	(decode-float (float 1.0 float))
+      (if (and (eq operation '-)
+	       (= significand 1.0-significand))
+	  (scale-float (typecase float
+			 (short-float short-float-negative-epsilon)
+			 (single-float single-float-negative-epsilon)
+			 (double-float double-float-negative-epsilon)
+			 (long-float long-float-negative-epsilon))
+		       (- exponent 1.0-exponent))
+	(scale-float (typecase float
+		       (short-float short-float-epsilon)
+		       (single-float single-float-epsilon)
+		       (double-float double-float-epsilon)
+		       (long-float long-float-epsilon))
+		     (- exponent 1.0-exponent))))))