ruby--ruby/spec/ruby/library/matrix/lup_decomposition/determinant_spec.rb

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

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

  describe "Matrix::LUPDecomposition#determinant" do
    it "returns the determinant when the matrix is square" do
      a = Matrix[[7, 8, 9], [14, 46, 51], [28, 82, 163]]
      a.lup.determinant.should == 15120 # == a.determinant
    end

    it "raises an error for rectangular matrices" do
      [
        Matrix[[7, 8, 9], [14, 46, 51]],
        Matrix[[7, 8], [14, 46], [28, 82]],
      ].each do |m|
        lup = m.lup
        -> {
          lup.determinant
        }.should raise_error(Matrix::ErrDimensionMismatch)
      end
    end
  end
end