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diff --git a/spec/ruby/library/matrix/imaginary_spec.rb b/spec/ruby/library/matrix/imaginary_spec.rb
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+++ b/spec/ruby/library/matrix/imaginary_spec.rb
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+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+require 'matrix'
+
+describe "Matrix#imaginary" do
+  it "returns a matrix with the imaginary part of the elements of the receiver" do
+    Matrix[ [1,   2], [3, 4] ].imaginary.should == Matrix[ [0,   0], [0, 0] ]
+    Matrix[ [1.9, Complex(1,1)], [Complex(-2,0.42), 4] ].imaginary.should == Matrix[ [0, 1], [0.42, 0] ]
+  end
+
+  it "returns empty matrices on the same size if empty" do
+    Matrix.empty(0, 3).imaginary.should == Matrix.empty(0, 3)
+    Matrix.empty(3, 0).imaginary.should == Matrix.empty(3, 0)
+  end
+
+  describe "for a subclass of Matrix" do
+    it "returns an instance of that subclass" do
+      MatrixSub.ins.imaginary.should.instance_of?(MatrixSub)
+    end
+  end
+end