matrix.rb: complex vector

* lib/matrix.rb (Vector#magnitude): accumulate squares of absolute
  values to fix for complex vector.  [ruby-dev:46100] [Bug #6966]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36887 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 21 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index a7ac1dfceb..82aa55bfd3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Sep  3 14:49:03 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/matrix.rb (Vector#magnitude): accumulate squares of absolute
+	  values to fix for complex vector.  [ruby-dev:46100] [Bug #6966]
+
 Mon Sep  3 10:09:36 2012  Martin Bosslet  <Martin.Bosslet@googlemail.com>
 
 	* ext/openssl/extconf.rb: Detect OpenSSL_FIPS macro
diff --git a/lib/matrix.rb b/lib/matrix.rb
index 8f57c73904..00fa762da6 100644
--- a/lib/matrix.rb
+++ b/lib/matrix.rb
@@ -1770,7 +1770,7 @@ class Vector
   #   Vector[5,8,2].r => 9.643650761
   #
   def magnitude
-    Math.sqrt(@elements.inject(0) {|v, e| v + e*e})
+    Math.sqrt(@elements.inject(0) {|v, e| v + e.abs2})
   end
   alias r magnitude
   alias norm magnitude
diff --git a/test/matrix/test_vector.rb b/test/matrix/test_vector.rb
index 582509fd20..18660df574 100644
--- a/test/matrix/test_vector.rb
+++ b/test/matrix/test_vector.rb
@@ -131,4 +131,19 @@ class TestVector < Test::Unit::TestCase
     assert_equal("Vector[1, 2, 3]", @v1.inspect)
   end
 
+  def test_magnitude
+    assert_in_epsilon(3.7416573867739413, @v1.norm)
+    assert_in_epsilon(3.7416573867739413, @v4.norm)
+  end
+
+  def test_complex_magnitude
+    bug6966 = '[ruby-dev:46100]'
+    v = Vector[Complex(0,1), 0]
+    assert_equal(1.0, v.norm, bug6966)
+  end
+
+  def test_rational_magnitude
+    v = Vector[Rational(1,2), 0]
+    assert_equal(0.5, v.norm)
+  end
 end