ruby--ruby/spec/ruby/library/matrix/eigenvalue_decomposition/eigenvalues_spec.rb

require_relative '../../../spec_helper'

ruby_version_is ""..."3.1" do
  require 'matrix'

  describe "Matrix::EigenvalueDecomposition#eigenvalues" do
    it "returns an array of complex eigenvalues for a rotation matrix" do
      Matrix[[ 1, 1],
             [-1, 1]].eigensystem.eigenvalues.sort_by{|v| v.imag}.should ==
      [ Complex(1, -1), Complex(1, 1)]
    end

    it "returns an array of real eigenvalues for a symmetric matrix" do
      Matrix[[1, 2],
             [2, 1]].eigensystem.eigenvalues.sort.map!{|x| x.round(10)}.should ==
      [ -1, 3 ]
    end

    it "returns an array of real eigenvalues for a matrix" do
      Matrix[[14, 16],
             [-6, -6]].eigensystem.eigenvalues.sort.map!{|x| x.round(10)}.should ==
      [ 2, 6 ]
    end
  end
end