X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=mjo%2Feja%2Feja_algebra.py;h=7c2eda211232ceac757a6d6caa40ae6722528349;hb=33b5476e1422a36972979e768f1829cec1b421a5;hp=d1658c2fba1aaf43e1115dee500bfd6b9c3602ac;hpb=f420787bd1cc7bfb467d31b5a1581e985434fb31;p=sage.d.git

diff --git a/mjo/eja/eja_algebra.py b/mjo/eja/eja_algebra.py
index d1658c2..7c2eda2 100644
--- a/mjo/eja/eja_algebra.py
+++ b/mjo/eja/eja_algebra.py
@@ -939,8 +939,9 @@ class MatrixEuclideanJordanAlgebra(FiniteDimensionalEuclideanJordanAlgebra):
         else:
             basis = ( (b/n) for (b,n) in izip(self.natural_basis(),
                                               self._basis_normalizers) )
-            field = self.base_ring().base_ring() # yeeeaahhhhhhh
-            J = MatrixEuclideanJordanAlgebra(field,
+
+            # Do this over the rationals and convert back at the end.
+            J = MatrixEuclideanJordanAlgebra(QQ,
                                              basis,
                                              self.rank(),
                                              normalize_basis=False)
@@ -949,7 +950,14 @@ class MatrixEuclideanJordanAlgebra(FiniteDimensionalEuclideanJordanAlgebra):
             # p might be missing some vars, have to substitute "optionally"
             pairs = izip(x.base_ring().gens(), self._basis_normalizers)
             substitutions = { v: v*c for (v,c) in pairs }
-            return p.subs(substitutions)
+            result = p.subs(substitutions)
+
+            # The result of "subs" can be either a coefficient-ring
+            # element or a polynomial. Gotta handle both cases.
+            if result in QQ:
+                return self.base_ring()(result)
+            else:
+                return result.change_ring(self.base_ring())
 
 
     @staticmethod
@@ -1532,7 +1540,7 @@ class QuaternionMatrixEuclideanJordanAlgebra(MatrixEuclideanJordanAlgebra):
         if M.ncols() != n:
             raise ValueError("the matrix 'M' must be square")
         if not n.mod(4).is_zero():
-            raise ValueError("the matrix 'M' must be a complex embedding")
+            raise ValueError("the matrix 'M' must be a quaternion embedding")
 
         # Use the base ring of the matrix to ensure that its entries can be
         # multiplied by elements of the quaternion algebra.