eja: simplify and unify the charpoly/rank stuff.

[sage.d.git] / mjo / eja / eja_element.py

diff --git a/mjo/eja/eja_element.py b/mjo/eja/eja_element.py
index 0f6a47cd4f10efbcb0298725c4ae26537eae6372..926f2bf57a612c71eab53b693daa1e3f559ad6bc 100644 (file)
--- a/mjo/eja/eja_element.py
+++ b/mjo/eja/eja_element.py
@@ -386,11 +386,11 @@ class FiniteDimensionalEuclideanJordanAlgebraElement(IndexedFreeModuleElement):
         """
         P = self.parent()
         r = P.rank()
-        p = P._charpoly_coeff(0)
-        # The _charpoly_coeff function already adds the factor of
-        # -1 to ensure that _charpoly_coeff(0) is really what
-        # appears in front of t^{0} in the charpoly. However,
-        # we want (-1)^r times THAT for the determinant.
+        p = P._charpoly_coefficients()[0]
+        # The _charpoly_coeff function already adds the factor of -1
+        # to ensure that _charpoly_coefficients()[0] is really what
+        # appears in front of t^{0} in the charpoly. However, we want
+        # (-1)^r times THAT for the determinant.
         return ((-1)**r)*p(*self.to_vector())
 
 
@@ -1220,8 +1220,18 @@ class FiniteDimensionalEuclideanJordanAlgebraElement(IndexedFreeModuleElement):
             sage: l0*c0 + l1*c1 == x
             True
 
+        The spectral decomposition should work in subalgebras, too::
+
+            sage: J = RealSymmetricEJA(4)
+            sage: (e0, e1, e2, e3, e4, e5, e6, e7, e8, e9) = J.gens()
+            sage: A = 2*e5 - 2*e8
+            sage: (lambda1, c1) = A.spectral_decomposition()[1]
+            sage: (J0, J5, J1) = J.peirce_decomposition(c1)
+            sage: (f0, f1, f2) = J1.gens()
+            sage: f0.spectral_decomposition()
+            [(0, 1.000000000000000?*f2), (1, 1.000000000000000?*f0)]
+
         """
-        P = self.parent()
         A = self.subalgebra_generated_by(orthonormalize_basis=True)
         result = []
         for (evalue, proj) in A(self).operator().spectral_decomposition():
@@ -1390,7 +1400,7 @@ class FiniteDimensionalEuclideanJordanAlgebraElement(IndexedFreeModuleElement):
             # the trace is an empty sum.
             return P.base_ring().zero()
 
-        p = P._charpoly_coeff(r-1)
+        p = P._charpoly_coefficients()[r-1]
         # The _charpoly_coeff function already adds the factor of
         # -1 to ensure that _charpoly_coeff(r-1) is really what
         # appears in front of t^{r-1} in the charpoly. However,