eja: add a randomly-failing test to the TODO.

[sage.d.git] / mjo / eja / TODO

diff --git a/mjo/eja/TODO b/mjo/eja/TODO
index 1ba2a464d066de3144512962c9e6e33fa8c2518e..f34fc34701a214afd3d086a675844b44619e5d9a 100644 (file)
--- a/mjo/eja/TODO
+++ b/mjo/eja/TODO
@@ -19,7 +19,8 @@ sage: a0 = (1/4)*X[4]**2*X[6]**2 - (1/2)*X[2]*X[5]*X[6]**2 - (1/2)*X[3]*X[4]*X[6
 6. Instead of storing a basis multiplication matrix, just make
    product_on_basis() a cached method and manually cache its
    entries. The cython cached method lookup should be faster than a
-   python-based matrix lookup anyway.
+   python-based matrix lookup anyway. NOTE: we should still be able
+   to recompute the table somehow. Is this worth it?
 
 7. What the ever-loving fuck is this shit?
 
@@ -28,13 +29,18 @@ sage: a0 = (1/4)*X[4]**2*X[6]**2 - (1/2)*X[2]*X[5]*X[6]**2 - (1/2)*X[3]*X[4]*X[6
        sage: e0*[[[[]]]]
        [[[[]]]]*e0
 
-8. Factor out a class for matrices with real embeddings (i.e. not the
-   octonions).
-
-9. In fact, could my octonion matrix algebra be generalized for any
+8. In fact, could my octonion matrix algebra be generalized for any
    algebra of matrices over the reals whose entries are not real? Then
    we wouldn't need real embeddings at all. They might even be fricking
    vector spaces if I did that...
 
-10. Add HurwitzMatrixAlgebra subclass between MatrixAlgebra and
-    OctonionMatrixAlgebra.
+9. Add HurwitzMatrixAlgebra subclass between MatrixAlgebra and
+   OctonionMatrixAlgebra.
+
+10. Every once in a long while, the test
+
+        sage: set_random_seed()
+        sage: x = random_eja().random_element()
+        sage: x.is_invertible() == (x.det() != 0)
+
+    in eja_element.py returns False.