* lib/matrix: Handle empty diagonal matrix case [fix GH-576]
  Patch by gogotanaka

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45524 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2014-04-07

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45525 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* test/matrix/test_matrix: Add tests for trivial cases [fix GH-576]
  Patch by gogotanaka

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45526 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* lib/matrix.rb: Add first_minor [fix GH-568]
  Patch by gogotanaka

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45527 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* lib/matrix.rb: Add Matrix#cofactor [fix GH-568]
  Patch by gogotanaka

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45528 b2dd03c8-39d4-4d8f-98ff-823fe69b080e