From 655cb34f17c2dc4b84aaf3fa99cceabb830138b8 Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Sat, 9 Jan 2010 20:35:28 +0000
Subject: [PATCH] * lib/matrix.rb (Matrix#inverse_from): use #quo. backported
 r9490.

* lib/matrix.rb (Matrix#determinant): ditto.  [ruby-core:27507]

* lib/matrix.rb (Matrix#rank): ditto.

* lib/matrix.rb (Matrix::Scalar#initialize): ditto.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@26263 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 lib/matrix.rb              | 2 +-
 test/matrix/test_matrix.rb | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/lib/matrix.rb b/lib/matrix.rb
index e0095e929e..222bf4b698 100644
--- a/lib/matrix.rb
+++ b/lib/matrix.rb
@@ -569,7 +569,7 @@ class Matrix
 
   #
   # Returns the inverse of the matrix.
-  #   Matrix[[1, 2], [2, 1]].inverse
+  #   Matrix[[-1, -1], [0, -1]].inverse
   #     => -1  1
   #         0 -1
   #
diff --git a/test/matrix/test_matrix.rb b/test/matrix/test_matrix.rb
index 8e0848de01..6b9b587c6d 100644
--- a/test/matrix/test_matrix.rb
+++ b/test/matrix/test_matrix.rb
@@ -144,4 +144,13 @@ class TestMatrix < Test::Unit::TestCase
       assert_equal 3, m.transpose.rank
     end
   end
+
+  def test_inverse
+    assert_equal(Matrix[[-1, 1], [0, -1]], Matrix[[-1, -1], [0, -1]].inverse)
+  end
+
+  def test_determinant
+    assert_equal(45, Matrix[[7,6], [3,9]].determinant)
+    assert_equal(-18, Matrix[[2,0,1],[0,-2,2],[1,2,3]].determinant)
+  end
 end