Import Debian changes 3a2-3debian/3a2-3

slib (3a2-3) unstable; urgency=low

  * Brought all source files up-to-date with upstream CVS.
  Repeat changes from version 3a2-1 in Makefile.

1 files changed, 24 insertions, 4 deletions

diff --git a/root.scm b/root.scm
index 0a56bc9..3cfdc19 100644
--- a/root.scm
+++ b/root.scm
@@ -40,11 +40,31 @@
 		 (next-fx (f next-x)))
 	    (cond ((>= (abs next-fx) (abs fx)) x)
 		  (else (loop next-x next-fx)))))))))))
+
+;;(define (integer-sqrt y)
+;;  (newton:find-integer-root (lambda (x) (- (* x x) y))
+;;			    (lambda (x) (* 2 x))
+;;			    (ash 1 (quotient (integer-length y) 2))))
+
+;;;; http://www.cs.cmu.edu/afs/cs/project/ai-repository/ai/lang/lisp/code/math/isqrt/isqrt.txt
+;;; Akira Kurihara
+;;; School of Mathematics
+;;; Japan Women's University
 ;@
-(define (integer-sqrt y)
-  (newton:find-integer-root (lambda (x) (- (* x x) y))
-			    (lambda (x) (* 2 x))
-			    (ash 1 (quotient (integer-length y) 2))))
+(define (integer-sqrt n)
+  (cond ((> n 24) (let* ((length/4 (quotient (- (integer-length n) 1) 4))
+			 (sqrt-top (integer-sqrt (ash n (* -2 length/4))))
+			 (init-value (ash sqrt-top length/4))
+			 (q (quotient n init-value))
+			 (iterated-value (quotient (+ init-value q) 2)))
+		    (if (odd? q) iterated-value
+			(let ((m (- iterated-value init-value)))
+			  (if (< (remainder n init-value) (* m m))
+			      (- iterated-value 1)
+			      iterated-value)))))
+	((> n 15) 4) ((> n 8) 3) ((> n 3) 2) ((> n 0) 1) ((> n -1) 0)
+	(else (slib:error 'integer-sqrt n))))
+
 ;@
 (define (newton:find-root f df/dx x_0 prec)
   (if (and (negative? prec) (integer? prec))