octonions: add a test for Cartesian products.

diff --git a/mjo/octonions.py b/mjo/octonions.py
index fb4b83396ea4d8bcac0bd058eae6406381b0eccc..2850545280b122cb8109324f4b6431ed0f5076ec 100644 (file)
--- a/mjo/octonions.py
+++ b/mjo/octonions.py
@@ -382,6 +382,16 @@ class OctonionMatrixAlgebra(HurwitzMatrixAlgebra):
         | e2 - e6 | e3 - e7 |
         +---------+---------+
 
+    ::
+
+        sage: A1 = OctonionMatrixAlgebra(1,QQ)
+        sage: A2 = OctonionMatrixAlgebra(1,QQ)
+        sage: cartesian_product([A1,A2])
+        Module of 1 by 1 matrices with entries in Octonion algebra with
+        base ring Rational Field over the scalar ring Rational Field (+)
+        Module of 1 by 1 matrices with entries in Octonion algebra with
+        base ring Rational Field over the scalar ring Rational Field
+
     TESTS::
 
         sage: set_random_seed()