Fix bug in `expt': zero raised to an integer power always returned

one.  Fix bug in `asin': real arguments of magnitude larger than one
should be handled specially.

diff --git a/v7/src/runtime/arith.scm b/v7/src/runtime/arith.scm
index 22562f5b558200931674a25e22df31930c075251..572759db6c585475d0784cf39bf8c614aa5c780d 100644 (file)
--- a/v7/src/runtime/arith.scm
+++ b/v7/src/runtime/arith.scm
@@ -1,6 +1,6 @@
 #| -*-Scheme-*-
 
-$Header: /Users/cph/tmp/foo/mit-scheme/mit-scheme/v7/src/runtime/arith.scm,v 1.9 1989/11/15 02:46:41 cph Exp $
+$Header: /Users/cph/tmp/foo/mit-scheme/mit-scheme/v7/src/runtime/arith.scm,v 1.10 1989/11/30 07:52:42 cph Exp $
 
 Copyright (c) 1989 Massachusetts Institute of Technology
 
@@ -238,9 +238,10 @@ MIT in each case. |#
            (positive-case n d)))))
 \f
 (define (int:expt b e)
-  (cond ((or (int:zero? b) (int:= 1 b)) 1)
-       ((int:positive? e)
-        (if (int:= 1 e)
+  (cond ((int:positive? e)
+        (if (or (int:= 1 e)
+                (int:zero? b)
+                (int:= 1 b))
             b
             (let loop ((b b) (e e) (answer 1))
               (let ((qr (int:divide e 2)))
@@ -1365,20 +1366,28 @@ MIT in each case. |#
 ;;;  This is ensured if z is in quadrants III or IV.
 
 (define (complex:asin z)
-  (if (recnum? z)
-      (let ((safe-case
-            (lambda (z)
-              (complex:-i*
-               (complex:log
-                (complex:+ (complex:+i* z)
-                           (complex:sqrt (complex:- 1 (complex:* z z)))))))))
-       (if (let ((imag (rec:imag-part z)))
-             (or (real:positive? imag)         ;get out of Q I and II
-                 (and (real:zero? imag)        ;and stay off negative reals
-                      (real:negative? (rec:real-part z)))))
-           (complex:negate (safe-case (complex:negate z)))
-           (safe-case z)))
-      ((copy real:asin) z)))
+  (let ((safe-case
+        (lambda (z)
+          (complex:-i*
+           (complex:log
+            (complex:+ (complex:+i* z)
+                       (complex:sqrt (complex:- 1 (complex:* z z)))))))))
+    (let ((unsafe-case
+          (lambda (z)
+            (complex:negate (safe-case (complex:negate z))))))
+      (cond ((recnum? z)
+            (if (let ((imag (rec:imag-part z)))
+                  (or (real:positive? imag)    ;get out of Q I and II
+                      (and (real:zero? imag)   ;and stay off negative reals
+                           (real:negative? (rec:real-part z)))))
+                (unsafe-case z)
+                (safe-case z)))
+           ((real:< z -1)
+            (unsafe-case z))
+           ((real:< 1 z)
+            (safe-case z))
+           (else
+            ((copy real:asin) z))))))
 
 (define (complex:acos z)
   (if (recnum? z)