eja: allow subalgebra_idempotent() to work in trivial EJAs.

Every element is nilpotent in a trivial EJA, but we also know the only
idempotent element in such an algebra: its sole occupant. So return it.

diff --git a/mjo/eja/eja_element.py b/mjo/eja/eja_element.py
index 3491b69230b0d430fdfa936b3399ebfc88259988..f44bee1c3f20d3040f0f77d8ff472b08c1bb5e9e 100644 (file)
--- a/mjo/eja/eja_element.py
+++ b/mjo/eja/eja_element.py
@@ -1285,6 +1285,9 @@ class FiniteDimensionalEuclideanJordanAlgebraElement(IndexedFreeModuleElement):
             True
 
         """
+        if self.parent().is_trivial():
+            return self
+
         if self.is_nilpotent():
             raise ValueError("this only works with non-nilpotent elements!")