From: Michael Orlitzky <michael@orlitzky.com>
Date: Mon, 9 Nov 2020 16:59:21 +0000 (-0500)
Subject: eja: improve how we get the "real part" of a possibly-complex trace.
X-Git-Url: http://gitweb.michael.orlitzky.com/?a=commitdiff_plain;h=e9cb8f877cfca9934dc67b6ab4f6ea585bba92d5;p=sage.d.git

eja: improve how we get the "real part" of a possibly-complex trace.
---

diff --git a/mjo/eja/eja_algebra.py b/mjo/eja/eja_algebra.py
index 10b8eb3..4bef201 100644
--- a/mjo/eja/eja_algebra.py
+++ b/mjo/eja/eja_algebra.py
@@ -1258,16 +1258,11 @@ class MatrixEuclideanJordanAlgebra(FiniteDimensionalEuclideanJordanAlgebra):
         Yu = cls.real_unembed(Y)
         tr = (Xu*Yu).trace()
 
-        if tr in RLF:
-            # It's real already.
-            return tr
-
-        # Otherwise, try the thing that works for complex numbers; and
-        # if that doesn't work, the thing that works for quaternions.
         try:
-            return tr.vector()[0] # real part, imag part is index 1
+            # Works in QQ, AA, RDF, et cetera.
+            return tr.real()
         except AttributeError:
-            # A quaternions doesn't have a vector() method, but does
+            # A quaternion doesn't have a real() method, but does
             # have coefficient_tuple() method that returns the
             # coefficients of 1, i, j, and k -- in that order.
             return tr.coefficient_tuple()[0]