require File.expand_path('../../../spec_helper', __FILE__) require File.expand_path('../fixtures/classes', __FILE__) require 'matrix' describe "Matrix.diagonal" do before :each do @m = Matrix.diagonal(10, 11, 12, 13, 14) end it "returns an object of type Matrix" do @m.should be_kind_of(Matrix) end it "returns a square Matrix of the right size" do @m.column_size.should == 5 @m.row_size.should == 5 end it "sets the diagonal to the arguments" do (0..4).each do |i| @m[i, i].should == i + 10 end end it "fills all non-diagonal cells with 0" do (0..4).each do |i| (0..4).each do |j| if i != j @m[i, j].should == 0 end end end end describe "for a subclass of Matrix" do it "returns an instance of that subclass" do MatrixSub.diagonal(1).should be_an_instance_of(MatrixSub) end end end describe "Matrix.diagonal?" do it "returns true for a diagonal Matrix" do Matrix.diagonal([1, 2, 3]).diagonal?.should be_true end it "returns true for a zero square Matrix" do Matrix.zero(3).diagonal?.should be_true end it "returns false for a non diagonal square Matrix" do Matrix[[0, 1], [0, 0]].diagonal?.should be_false Matrix[[1, 2, 3], [1, 2, 3], [1, 2, 3]].diagonal?.should be_false end it "returns true for an empty 0x0 matrix" do Matrix.empty(0,0).diagonal?.should be_true end it "raises an error for rectangular matrices" do [ Matrix[[0], [0]], Matrix[[0, 0]], Matrix.empty(0, 2), Matrix.empty(2, 0), ].each do |rectangual_matrix| lambda { rectangual_matrix.diagonal? }.should raise_error(Matrix::ErrDimensionMismatch) end end end