eja: rename operator_inner_product -> operator_trace inner_product.

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

diff --git a/mjo/eja/TODO b/mjo/eja/TODO
index 03bf40459e26805a2b2d6e3bae114779f0de57d3..b0d5378fab6ed7c7c981aaf0fd9a044ca18a1b07 100644 (file)
--- a/mjo/eja/TODO
+++ b/mjo/eja/TODO
@@ -1,25 +1,20 @@
-1. Finish CartesianProductEJA: add to_matrix(),
-   random_instance(),... methods. This will require rethinking what a
-   "matrix representation" and "matrix space" means for a cartesian
-   product algebra. Do we want our matrix basis to consist of ordered
-   pairs (or triples, or...)? Should the matrix_space() of the algebra
-   be the cartesian product of the factors' matrix spaces? Can we just
-   fix the matrix basis/space after we call the FDEJA initializer?
+1. Add references and start citing them.
 
-2. Add references and start citing them.
+2. Profile (and fix?) any remaining slow operations.
 
-3. Implement the octonion simple EJA.
+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. Pre-cache charpoly for some small algebras?
+4. Add dimension bounds on any tests over AA that compute element
+   subalgebras.
 
-RealSymmetricEJA(4):
+5. The rational_algebra() stuff doesn't really belong in classes that
+   don't derive from RationalBasisEJA or its as-yet-nonexistent
+   element class.
 
-sage: F = J.base_ring()
-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]*X[7] + (F(2).sqrt()/2)*X[1]*X[5]*X[6]*X[7] + (1/4)*X[3]**2*X[7]**2 - (1/2)*X[0]*X[5]*X[7]**2 + (F(2).sqrt()/2)*X[2]*X[3]*X[6]*X[8] - (1/2)*X[1]*X[4]*X[6*X[8] - (1/2)*X[1]*X[3]*X[7]*X[8] + (F(2).sqrt()/2)*X[0]*X[4]*X[7]*X[8] + (1/4)*X[1]**2*X[8]**2 - (1/2)*X[0]*X[2]*X[8]**2 - (1/2)*X[2]*X[3]**2*X[9] + (F(2).sqrt()/2)*X[1]*X[3]*X[4]*X[9] - (1/2)*X[0]*X[4]**2*X[9] - (1/2)*X[1]**2*X[5]*X[9] + X[0]*X[2]*X[5]*X[9]
-
-5. The main EJA element constructor is happy to convert between
-   e.g. HadamardEJA(3) and JordanSpinEJA(3).
-
-6. Profile the construction of "large" matrix algebras (like the
-   15-dimensional QuaternionHermitianAlgebra(3)) to find out why
-   they're so slow.
+6. Add special det/trace method overrides for the algebras where we
+   know them? The only reason this might be tricky is because the
+   obvious solution is to subclass EJAElement, but then we might
+   collide with e.g. the Cartesian product element subclass.