From 1ba4748f125c32d51ed1b3b89188f34546c9136f Mon Sep 17 00:00:00 2001
From: Michael Orlitzky <michael@orlitzky.com>
Date: Sun, 22 Nov 2020 22:13:52 -0500
Subject: [PATCH] eja: check the (co)domain of each EJA operator.

---
 mjo/eja/eja_operator.py | 46 ++++++++++++++++++++++++++++++++++++-----
 1 file changed, 41 insertions(+), 5 deletions(-)

diff --git a/mjo/eja/eja_operator.py b/mjo/eja/eja_operator.py
index 667e3d5..468a921 100644
--- a/mjo/eja/eja_operator.py
+++ b/mjo/eja/eja_operator.py
@@ -3,12 +3,48 @@ from sage.categories.all import FreeModules
 from sage.categories.map import Map
 
 class FiniteDimensionalEuclideanJordanAlgebraOperator(Map):
+    r"""
+    An operator between two finite-dimensional Euclidean Jordan algebras.
+
+    SETUP::
+
+        sage: from mjo.eja.eja_algebra import HadamardEJA
+        sage: from mjo.eja.eja_operator import FiniteDimensionalEuclideanJordanAlgebraOperator
+
+    EXAMPLES:
+
+    The domain and codomain must be finite-dimensional Euclidean
+    Jordan algebras; if either is not, then an error is raised::
+
+        sage: J = HadamardEJA(3)
+        sage: V = VectorSpace(J.base_ring(), 3)
+        sage: M = matrix.identity(J.base_ring(), 3)
+        sage: FiniteDimensionalEuclideanJordanAlgebraOperator(V,J,M)
+        Traceback (most recent call last):
+        ...
+        TypeError: domain must be a finite-dimensional Euclidean
+        Jordan algebra
+        sage: FiniteDimensionalEuclideanJordanAlgebraOperator(J,V,M)
+        Traceback (most recent call last):
+        ...
+        TypeError: codomain must be a finite-dimensional Euclidean
+        Jordan algebra
+
+    """
+
     def __init__(self, domain_eja, codomain_eja, mat):
-        # if not (
-        #   isinstance(domain_eja, FiniteDimensionalEuclideanJordanAlgebra) and
-        #   isinstance(codomain_eja, FiniteDimensionalEuclideanJordanAlgebra) ):
-        #     raise ValueError('(co)domains must be finite-dimensional Euclidean '
-        #                      'Jordan algebras')
+        from mjo.eja.eja_algebra import FiniteDimensionalEuclideanJordanAlgebra
+
+        # I guess we should check this, because otherwise you could
+        # pass in pretty much anything algebraish.
+        if not isinstance(domain_eja,
+                          FiniteDimensionalEuclideanJordanAlgebra):
+            raise TypeError('domain must be a finite-dimensional '
+                            'Euclidean Jordan algebra')
+        if not isinstance(codomain_eja,
+                          FiniteDimensionalEuclideanJordanAlgebra):
+            raise TypeError('codomain must be a finite-dimensional '
+                            'Euclidean Jordan algebra')
 
         F = domain_eja.base_ring()
         if not (F == codomain_eja.base_ring()):
-- 
2.44.2