eja: append to an existing TODO.

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

diff --git a/mjo/eja/TODO b/mjo/eja/TODO
index 1def3d2e9fd8cf381ae743344ce670a13f226438..fb89e5edc905cea8475fb2349b3318e4aad22947 100644 (file)
--- a/mjo/eja/TODO
+++ b/mjo/eja/TODO
@@ -2,19 +2,11 @@
 
 2. Profile (and fix?) any remaining slow operations.
 
-3. 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. Example:
-
-       sage: J1 = ComplexHermitianEJA(2)
-       sage: J2 = TrivialEJA()
-       sage: J = cartesian_product([J1,J2])
-       sage: x = J.from_vector(vector(QQ, [-1, -1/2, -1/2, -1/2]))
-       sage: x.is_invertible()
-       True
-       sage: x.det()
-       0
+3. When we take a Cartesian product involving a trivial algebra, we
+   could easily cache the identity and charpoly coefficients using
+   the nontrivial factor. On the other hand, it's nice that we can
+   test out some alternate code paths...
+
+4. Conjecture: if x = (x1,x2), then det(x) = det(x1)det(x2). This
+   should be used to fix the fact that det(x) is monstrously slow in
+   Cartesian product algebras, and thus randomly in the doctests.