marcandre	2017-03-15 05:09:30 +0900 (Wed, 15 Mar 2017)

  New Revision: 57976

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=57976

  Log:
    * lib/matrix.rb: Add Vector.zero and Vector#zero?
      Patch by Chia-sheng Chen [#13208]

  Modified files:
    trunk/lib/matrix.rb
    trunk/test/matrix/test_vector.rb
Index: test/matrix/test_vector.rb
===================================================================
--- test/matrix/test_vector.rb	(revision 57975)
+++ test/matrix/test_vector.rb	(revision 57976)
@@ -11,6 +11,13 @@ class TestVector < Test::Unit::TestCase https://github.com/ruby/ruby/blob/trunk/test/matrix/test_vector.rb#L11
     @w1 = Vector[2,3,4]
   end
 
+  def test_zero
+    assert_equal Vector[0, 0, 0, 0], Vector.zero(4)
+    assert_equal Vector[], Vector.zero(0)
+    assert_raise(ArgumentError) { Vector.zero(-1) }
+    assert Vector[0, 0, 0, 0].zero?
+  end
+
   def test_basis
     assert_equal(Vector[1, 0, 0], Vector.basis(size: 3, index: 0))
     assert_raise(ArgumentError) { Vector.basis(size: -1, index: 2) }
Index: lib/matrix.rb
===================================================================
--- lib/matrix.rb	(revision 57975)
+++ lib/matrix.rb	(revision 57976)
@@ -1685,6 +1685,7 @@ end https://github.com/ruby/ruby/blob/trunk/lib/matrix.rb#L1685
 # * Vector.[](*array)
 # * Vector.elements(array, copy = true)
 # * Vector.basis(size: n, index: k)
+# * Vector.zero(n)
 #
 # To access elements:
 # * #[](i)
@@ -1697,6 +1698,7 @@ end https://github.com/ruby/ruby/blob/trunk/lib/matrix.rb#L1698
 # * #angle_with(v)
 # * Vector.independent?(*vs)
 # * #independent?(*vs)
+# * #zero?
 #
 # Vector arithmetic:
 # * #*(x) "is matrix or number"
@@ -1769,6 +1771,17 @@ class Vector https://github.com/ruby/ruby/blob/trunk/lib/matrix.rb#L1771
   end
 
   #
+  # Return a zero vector.
+  #
+  #    Vector.zero(3) => Vector[0, 0, 0]
+  #
+  def Vector.zero(size)
+    raise ArgumentError, "invalid size (#{size} for 0..)" if size < 0
+    array = Array.new(size, 0)
+    new convert_to_array(array, false)
+  end
+
+  #
   # Vector.new is private; use Vector[] or Vector.elements to create.
   #
   def initialize(array)
@@ -1882,6 +1895,13 @@ class Vector https://github.com/ruby/ruby/blob/trunk/lib/matrix.rb#L1895
     self.class.independent?(self, *vs)
   end
 
+  #
+  # Returns +true+ iff all elements are zero.
+  #
+  def zero?
+    all?(&:zero?)
+  end
+
   #--
   # COMPARING -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
   #++

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