0.8.3.51:

	Fix (LCM 0 0)

diff --git a/NEWS b/NEWS
index a6c9ad7..af2dbaf 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -2048,6 +2048,8 @@ changes in sbcl-0.8.4 relative to sbcl-0.8.3:
        upper bounding index of a substring in case :JUNK-ALLOWED NIL.
     ** PARSE-INTEGER returned an incorrect index being applied to a
        displaced string.
+    ** LCM with two arguments of 0 returns 0 rather than signalling
+       DIVISION-BY-ZERO.
 
 planned incompatible changes in 0.8.x:
   * (not done yet, but planned:) When the profiling interface settles

diff --git a/src/code/numbers.lisp b/src/code/numbers.lisp
index c2a1a6b..f5cbddf 100644 (file)
--- a/src/code/numbers.lisp
+++ b/src/code/numbers.lisp
@@ -1263,13 +1263,20 @@
 
 (defun two-arg-lcm (n m)
   (declare (integer n m))
-  (let ((m (abs m))
-        (n (abs n)))
-    (multiple-value-bind (max min)
-        (if (> m n)
-            (values m n)
-            (values n m))
-      (* (truncate max (gcd n m)) min))))
+  (if (or (zerop n) (zerop m))
+      0
+      ;; KLUDGE: I'm going to assume that it was written this way
+      ;; originally for a reason.  However, this is a somewhat
+      ;; complicated way of writing the algorithm in the CLHS page for
+      ;; LCM, and I don't know why.  To be investigated.  -- CSR,
+      ;; 2003-09-11
+      (let ((m (abs m))
+           (n (abs n)))
+       (multiple-value-bind (max min)
+           (if (> m n)
+               (values m n)
+               (values n m))
+         (* (truncate max (gcd n m)) min)))))
 
 ;;; Do the GCD of two integer arguments. With fixnum arguments, we use the
 ;;; binary GCD algorithm from Knuth's seminumerical algorithms (slightly

diff --git a/tests/arith.pure.lisp b/tests/arith.pure.lisp
index 00ff6af..1f26fcc 100644 (file)
--- a/tests/arith.pure.lisp
+++ b/tests/arith.pure.lisp
@@ -110,6 +110,7 @@
   (assert (= (gcd 0 x) (abs x))))
 ;;; LCM returns a non-negative number
 (assert (= (lcm 4 -10) 20))
+(assert (= (lcm 0 0) 0))
 
 ;;; PPC bignum arithmetic bug:
 (multiple-value-bind (quo rem)

diff --git a/version.lisp-expr b/version.lisp-expr
index 60fbb52..cbc4c42 100644 (file)
--- a/version.lisp-expr
+++ b/version.lisp-expr
@@ -17,4 +17,4 @@
 ;;; checkins which aren't released. (And occasionally for internal
 ;;; versions, especially for internal versions off the main CVS
 ;;; branch, it gets hairier, e.g. "0.pre7.14.flaky4.13".)
-"0.8.3.50"
+"0.8.3.51"