From: Michael Orlitzky <michael@orlitzky.com>
Date: Sat, 24 Aug 2019 04:06:56 +0000 (-0400)
Subject: eja: fix a bug in the charpoly fast path for complex/quaternion matrices.
X-Git-Url: https://gitweb.michael.orlitzky.com/?a=commitdiff_plain;h=ed093213197d2ffa48849b0089ebe391b7574b93;p=sage.d.git

eja: fix a bug in the charpoly fast path for complex/quaternion matrices.
---

diff --git a/mjo/eja/eja_algebra.py b/mjo/eja/eja_algebra.py
index 2a5e624..8ab1381 100644
--- a/mjo/eja/eja_algebra.py
+++ b/mjo/eja/eja_algebra.py
@@ -930,7 +930,9 @@ class MatrixEuclideanJordanAlgebra(FiniteDimensionalEuclideanJordanAlgebra):
             # with had entries in a nice field.
             return super(MatrixEuclideanJordanAlgebra, self)._charpoly_coeff(i)
         else:
-            n = self.natural_basis_space().nrows()
+            # If we didn't unembed first, this number would be wrong
+            # by a power-of-two factor for complex/quaternion matrices.
+            n = self.real_unembed(self.natural_basis_space().zero()).nrows()
             field = self.base_ring().base_ring() # yeeeeaaaahhh
             J = self.__class__(n, field, False)
             (_,x,_,_) = J._charpoly_matrix_system()