require_relative '../../spec_helper'
require_relative 'fixtures/classes'
require 'matrix'

describe "Matrix#real?" do
  it "returns true for matrices with all real entries" do
    Matrix[ [1,   2], [3, 4] ].real?.should be_true
    Matrix[ [1.9, 2], [3, 4] ].real?.should be_true
  end

  it "returns true for empty matrices" do
    Matrix.empty.real?.should be_true
  end

  it "returns false if one element is a Complex" do
    Matrix[ [Complex(1,1), 2], [3, 4] ].real?.should be_false
  end

  # Guard against the Mathn library
  guard -> { !defined?(Math.rsqrt) } do
    it "returns false if one element is a Complex whose imaginary part is 0" do
      Matrix[ [Complex(1,0), 2], [3, 4] ].real?.should be_false
    end
  end
end

describe "Matrix#real" do
  it "returns a matrix with the real part of the elements of the receiver" do
    Matrix[ [1,   2], [3, 4] ].real.should == Matrix[ [1,   2], [3, 4] ]
    Matrix[ [1.9, Complex(1,1)], [Complex(-0.42, 0), 4] ].real.should == Matrix[ [1.9, 1], [-0.42, 4] ]
  end

  it "returns empty matrices on the same size if empty" do
    Matrix.empty(0, 3).real.should == Matrix.empty(0, 3)
    Matrix.empty(3, 0).real.should == Matrix.empty(3, 0)
  end

  describe "for a subclass of Matrix" do
    it "returns an instance of that subclass" do
      MatrixSub.ins.real.should be_an_instance_of(MatrixSub)
    end
  end
end