Perfect numbers: Difference between revisions

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@@ Line 938: / Line 938: @@
     tf = total == n;
 end</lang>
+Faster for large numbers:
-Somewhat faster:
 <lang MATLAB>function tf = isPerfect(n)
-    total = 0;
+    if n < 2
-    k = 1;
+        tf = false;
+    else
-    while k < n && total <= n
-        if ~mod(n, k)
+        total = 0;
-            total = total+k;
+        k = 1;
+        upperLimit = ceil(n/2);
+        while k <= upperLimit && total <= n
+            if ~mod(n, k)
+                total = total+k;
+            end
+            k = k+1;
         end
-        k = k+1;
+        tf = total == n;
     end
-    tf = total == n;
 end</lang>