diff options
| author | yugui <yugui@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2009-07-13 13:51:49 +0000 |
|---|---|---|
| committer | yugui <yugui@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2009-07-13 13:51:49 +0000 |
| commit | 7287b852da95b3bee1395fd80752e62b686da294 (patch) | |
| tree | f22c154e749662d907df5b6fdb98e3208b8528e0 | |
| parent | 0fefd1902329f72434e859bd77a7ea5a114c00ff (diff) | |
* 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
| -rw-r--r-- | ChangeLog | 7 | ||||
| -rw-r--r-- | lib/prime.rb | 7 | ||||
| -rw-r--r-- | test/test_prime.rb | 5 |
3 files changed, 18 insertions, 1 deletions
@@ -1,3 +1,10 @@ +Mon Jul 13 22:49:50 2009 Yuki Sonoda (Yugui) <yugui@yugui.jp> + + * lib/prime.rb (Prime#prime_division): now decomposes + negative integer into a decomposition with element [-1, 1]. + + * test/test_prime.rb: test for it. + Mon Jul 13 22:28:03 2009 NAKAMURA Usaku <usa@ruby-lang.org> * io.c (pipe_open): handles leaked on win32 when an error occurs. 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) diff --git a/test/test_prime.rb b/test/test_prime.rb index e7c025a55a..307d53afb3 100644 --- a/test/test_prime.rb +++ b/test/test_prime.rb @@ -98,10 +98,15 @@ class TestPrime < Test::Unit::TestCase def test_prime_division pd = PRIMES.inject(&:*).prime_division assert_equal PRIMES.map{|p| [p, 1]}, pd + + pd = (-PRIMES.inject(&:*)).prime_division + assert_equal [-1, *PRIMES].map{|p| [p, 1]}, pd end def test_from_prime_division assert_equal PRIMES.inject(&:*), Integer.from_prime_division(PRIMES.map{|p| [p,1]}) + + assert_equal -PRIMES.inject(&:*), Integer.from_prime_division([[-1, 1]] + PRIMES.map{|p| [p,1]}) end def test_prime? |