* lib/matrix.rb: Add Vector#cross_product, patch by Luis Ezcurdia

  [fix GH-276] [rubyspec:81eec89a124]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40273 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 12 insertions, 0 deletions

diff --git a/lib/matrix.rb b/lib/matrix.rb
index b1d1a5c2bd..9bda8855ce 100644
--- a/lib/matrix.rb
+++ b/lib/matrix.rb
@@ -1519,6 +1519,7 @@ end
 #
 # Vector functions:
 # * #inner_product(v)
+# * #cross_product(v)
 # * #collect
 # * #magnitude
 # * #map
@@ -1758,6 +1759,17 @@ class Vector
   end
 
   #
+  # Returns the cross product of this vector whit the other.
+  #   Vector[1, 0, 0].cross_product Vector[0, 1, 0]   => Vector[0, 0, 1]
+  #
+  def cross_product(v)
+    Vector.Raise ErrDimensionMismatch unless size == v.size && v.size == 3
+    Vector[ v[1]*@elements[2] - v[2]*@elements[1],
+            v[2]*@elements[0] - v[0]*@elements[2],
+            v[0]*@elements[1] - v[1]*@elements[0] ]
+  end
+
+  #
   # Like Array#collect.
   #
   def collect(&block) # :yield: e