[gnome-calculator] Improved factorization for numbers less than 2^64-1.

[Arth Patel <arthpatel src gnome org>]

commit 8664913437686a98c566935b70119fd3b835477a
Author: Garima Joshi <gjoshi0311 gmail com>
Date:   Wed Apr 24 17:31:34 2013 +0530

    Improved factorization for numbers less than 2^64-1.

 src/number.vala |   38 ++++++++++++++++++++++++++++++++++++++
 1 files changed, 38 insertions(+), 0 deletions(-)
---
diff --git a/src/number.vala b/src/number.vala
index 4f40de1..5805502 100644
--- a/src/number.vala
+++ b/src/number.vala
@@ -1646,6 +1646,21 @@ public class Number
             return factors;
         }
 
+        // if value < 2^64-1, call for factorize_uint64 function which deals in integers
+
+        uint64 num = 1;
+        num = num << 63;
+        num += (num - 1);
+        var int_max = new Number.unsigned_integer (num);
+
+        if (value.compare (int_max) <= 0)
+        {
+            var factors_int64 = factorize_uint64 (value.to_unsigned_integer ());
+            if (is_negative ())
+                factors_int64.data = factors_int64.data.invert_sign ();
+            return factors_int64;
+        }
+
         var divisor = new Number.integer (2);
         while (true)
         {
@@ -1686,6 +1701,29 @@ public class Number
         return factors;
     }
 
+    public List<Number?> factorize_uint64 (uint64 n)
+    {
+        var factors = new List<Number?> ();
+        while (n % 2 == 0)
+        {
+            n /= 2;
+            factors.append (new Number.unsigned_integer (2));
+        }
+
+        for (uint64 divisor = 3; divisor <= n / divisor; divisor += 2)
+        {
+            while (n % divisor == 0)
+            {
+                n /= divisor;
+                factors.append (new Number.unsigned_integer (divisor));
+            }
+        }
+
+        if (n > 1)
+            factors.append (new Number.unsigned_integer (n));
+        return factors;
+    }
+
     private Number copy ()
     {
         var z = new Number ();