From: Michael Orlitzky <michael@orlitzky.com>
Date: Fri, 5 Jul 2019 00:22:46 +0000 (-0400)
Subject: eja: fix the basis order for Sn.
X-Git-Url: https://gitweb.michael.orlitzky.com/?a=commitdiff_plain;h=d08aa61e7c6adc5d6bed4c23797959c483b021bb;p=sage.d.git

eja: fix the basis order for Sn.
---

diff --git a/mjo/eja/euclidean_jordan_algebra.py b/mjo/eja/euclidean_jordan_algebra.py
index 52a8a74..802171f 100644
--- a/mjo/eja/euclidean_jordan_algebra.py
+++ b/mjo/eja/euclidean_jordan_algebra.py
@@ -641,8 +641,16 @@ def eja_sn(dimension, field=QQ):
     def mat2vec(m):
         return vector(field, m.list())
 
+    def vec2mat(v):
+        return matrix(field, dimension, v.list())
+
     W = V.span( mat2vec(s) for s in S )
 
+    # Taking the span above reorders our basis (thanks, jerk!) so we
+    # need to put our "matrix basis" in the same order as the
+    # (reordered) vector basis.
+    S = [ vec2mat(b) for b in W.basis() ]
+
     for s in S:
         # Brute force the multiplication-by-s matrix by looping
         # through all elements of the basis and doing the computation