Matrix: Add #reflexive? method. [Fix GH-1730]

Adapted from a patch by Yilo

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64796 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/matrix.rb b/lib/matrix.rb
index 7639b1de6d..62852bdad0 100644
--- a/lib/matrix.rb
+++ b/lib/matrix.rb
@@ -814,6 +814,15 @@ class Matrix
   end
 
   #
+  # Returns +true+ if this is a reflexive matrix.
+  # Raises an error if matrix is not square.
+  #
+  def reflexive?
+    Matrix.Raise ErrDimensionMismatch unless square?
+    each(:diagonal).all? { |e| e == 1 }
+  end
+
+  #
   # Returns +true+ if this is a unitary matrix
   # Raises an error if matrix is not square.
   #