X-Git-Url: http://git.kpe.io/?a=blobdiff_plain;f=math.lisp;h=e9118443fdec24c716cf21898b42615ce5973692;hb=27a9a1fba69e1f861a0dbbb1ad321d2e60ccdb8f;hp=9a6862bad3f6168196b2838b69ef8eed1505f092;hpb=d1e9c5969a0eecb7923dc350754ea9ab50417a1e;p=kmrcl.git

diff --git a/math.lisp b/math.lisp
index 9a6862b..e911844 100644
--- a/math.lisp
+++ b/math.lisp
@@ -7,7 +7,7 @@
 ;;;; Programmer:    Kevin M. Rosenberg
 ;;;; Date Started:  Nov 2002
 ;;;;
-;;;; $Id: math.lisp,v 1.2 2003/04/28 16:07:42 kevin Exp $
+;;;; $Id$
 ;;;;
 ;;;; This file, part of KMRCL, is Copyright (c) 2002 by Kevin M. Rosenberg
 ;;;;
@@ -17,7 +17,7 @@
 ;;;; *************************************************************************
 
 
-(in-package :kmrcl)
+(in-package #:kmrcl)
 
 (defun deriv (f dx)
   #'(lambda (x)
@@ -28,3 +28,48 @@
     (funcall (deriv #'sin 1d-8) x))
 
 ;;; (sin^ pi)
+
+(defmacro ensure-integer (obj)
+  "Ensure object is an integer. If it is a string, then parse it"
+  `(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))))