X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=mjo%2Feja%2FTODO;h=25ef99df92da5f41595c609cdea9ae5d245cd1fe;hb=e4d568e25c62d79a2dbe34b81ee4dc21edf09316;hp=239f3e45b03a51adf0e772d967d48804f9cddf3a;hpb=d373c76a0ae0a1e7ba876d09359f84da40a7ea16;p=sage.d.git

diff --git a/mjo/eja/TODO b/mjo/eja/TODO
index 239f3e4..25ef99d 100644
--- a/mjo/eja/TODO
+++ b/mjo/eja/TODO
@@ -1,14 +1,23 @@
-0. Add tests for orthogonality in the Peirce decomposition.
+1. Finish DirectSumEJA: add to_matrix(), random_instance(),
+   one()... methods. Make it subclass RationalBasisEuclideanJordanAlgebra.
+   This is not a general direct sum / cartesian product implementation,
+   it's used only with the other rationalbasis algebras (to make non-
+   simple EJAs out of the simple ones).
 
-1. Add CartesianProductEJA.
+2. Add references and start citing them.
 
-2. Check the axioms in the constructor when check != False?
+3. Implement the octonion simple EJA.
 
-3. Add references and start citing them.
+4. Pre-cache charpoly for some small algebras?
 
-4. Implement the octonion simple EJA.
+RealSymmetricEJA(4):
 
-5. Factor out the unit-norm basis (and operator symmetry) tests once
-   all of the algebras pass.
+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]
 
-6. The EJA random element method only returns two summands by default.
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+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.
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