test_matrix.rb: Refactor on Matrix#determinant
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50448 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
test_matrix.rb: Refactor on Matrix#determinant
Matrix#determinant, by merging with test_det for an alias method
det. [Fix GH-897]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50448 b2dd03c8-39d4-4d8f-98ff-823fe69b080e