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* lib/prime.rb (Prime#prime_division): now decomposes

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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
This commit is contained in:
yugui 2009-07-13 13:51:49 +00:00
parent 0fefd19023
commit 7287b852da
3 changed files with 18 additions and 1 deletions
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7
ChangeLog
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@ -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> 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. * io.c (pipe_open): handles leaked on win32 when an error occurs.

7
lib/prime.rb
View file

@ -194,7 +194,12 @@ class Prime
# #
def prime_division(value, generator= Prime::Generator23.new) def prime_division(value, generator= Prime::Generator23.new)
raise ZeroDivisionError if value == 0 raise ZeroDivisionError if value == 0
pv = [] if value < 0
value = -value
pv = [[-1, 1]]
else
pv = []
end
for prime in generator for prime in generator
count = 0 count = 0
while (value1, mod = value.divmod(prime) while (value1, mod = value.divmod(prime)

5
test/test_prime.rb
View file

@ -98,10 +98,15 @@ class TestPrime < Test::Unit::TestCase
def test_prime_division def test_prime_division
pd = PRIMES.inject(&:*).prime_division pd = PRIMES.inject(&:*).prime_division
assert_equal PRIMES.map{|p| [p, 1]}, pd assert_equal PRIMES.map{|p| [p, 1]}, pd
pd = (-PRIMES.inject(&:*)).prime_division
assert_equal [-1, *PRIMES].map{|p| [p, 1]}, pd
end end
def test_from_prime_division 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(PRIMES.map{|p| [p,1]})
assert_equal -PRIMES.inject(&:*), Integer.from_prime_division([[-1, 1]] + PRIMES.map{|p| [p,1]})
end end
def test_prime? def test_prime?