eja: test the nonnegativity of trace() for squares.

diff --git a/mjo/eja/eja_element.py b/mjo/eja/eja_element.py
index 0fd1c5f2032151de7d752494b4117825af3109a3..bef1289bbdd3820b990cf0b3ae0f4ff7334f3b01 100644 (file)
--- a/mjo/eja/eja_element.py
+++ b/mjo/eja/eja_element.py
@@ -1512,6 +1512,12 @@ class FiniteDimensionalEJAElement(IndexedFreeModuleElement):
             sage: (alpha*x + y).trace() == alpha*x.trace() + y.trace()
             True
 
             sage: (alpha*x + y).trace() == alpha*x.trace() + y.trace()
             True
 

+        The trace of a square is nonnegative::
+
+            sage: x = random_eja().random_element()
+            sage: (x*x).trace() >= 0
+            True
+

         """
         P = self.parent()
         r = P.rank()
         """
         P = self.parent()
         r = P.rank()