1 files changed, 21 insertions, 0 deletions
diff --git a/spec/ruby/library/matrix/lup_decomposition/determinant_spec.rb b/spec/ruby/library/matrix/lup_decomposition/determinant_spec.rb
new file mode 100644
index 0000000000..f73c65ba8f
--- /dev/null
+++ b/spec/ruby/library/matrix/lup_decomposition/determinant_spec.rb
@@ -0,0 +1,21 @@
+require File.expand_path('../../../../spec_helper', __FILE__)
+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
+      lambda {
+        lup.determinant
+      }.should raise_error(Matrix::ErrDimensionMismatch)
+    end
+  end
+end