From 7287b852da95b3bee1395fd80752e62b686da294 Mon Sep 17 00:00:00 2001
From: yugui <yugui@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Mon, 13 Jul 2009 13:51:49 +0000
Subject: * lib/prime.rb (Prime#prime_division): now decomposes   negative
 integer into a decomposition with element [-1, 1].

* test/test_prime.rb: test for it.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@24091 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 lib/prime.rb | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

(limited to 'lib/prime.rb')

diff --git a/lib/prime.rb b/lib/prime.rb
index 50b78d9b0e..68253897ca 100644
--- a/lib/prime.rb
+++ b/lib/prime.rb
@@ -194,7 +194,12 @@ class Prime
   #
   def prime_division(value, generator= Prime::Generator23.new)
     raise ZeroDivisionError if value == 0
-    pv = []
+    if value < 0
+      value = -value
+      pv = [[-1, 1]]
+    else
+      pv = []
+    end
     for prime in generator
       count = 0
       while (value1, mod = value.divmod(prime)
-- 
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