matrix_algebra: put basis in the usual (row,column) order.

[sage.d.git] / mjo / matrix_algebra.py

diff --git a/mjo/matrix_algebra.py b/mjo/matrix_algebra.py
index c38e8556203243536fc0af87078840f82e2d57cb..84aa8d28bb3de9e6797b9b0a209eb96c3a14dc22 100644 (file)
--- a/mjo/matrix_algebra.py
+++ b/mjo/matrix_algebra.py
@@ -198,14 +198,16 @@ class MatrixAlgebra(CombinatorialFreeModule):
         # sticking a "1" in each position doesn't give us a basis for
         # the space. We actually need to stick each of e0, e1, ...  (a
         # basis for the entry algebra itself) into each position.
-        I = range(n)
-        J = range(n)
         self._entry_algebra = entry_algebra
-        entry_basis = entry_algebra.gens()
 
-        basis_indices = [(i,j,e) for i in range(n)
-                                 for j in range(n)
-                                 for e in entry_algebra.gens()]
+        # Needs to make the (overridden) method call when, for example,
+        # the entry algebra is the complex numbers and its gens() method
+        # lies to us.
+        entry_basis = self.entry_algebra_gens()
+
+        basis_indices = [(i,j,e) for j in range(n)
+                                 for i in range(n)
+                                 for e in entry_basis]
 
         super().__init__(scalars,
                          basis_indices,
@@ -227,6 +229,17 @@ class MatrixAlgebra(CombinatorialFreeModule):
         """
         return self._entry_algebra
 
+    def entry_algebra_gens(self):
+        r"""
+        Return a tuple of the generators of (that is, a basis for) the
+        entries of this matrix algebra.
+
+        This can be overridden in subclasses to work around the
+        inconsistency in the ``gens()`` methods of the various
+        entry algebras.
+        """
+        return self.entry_algebra().gens()
+
     def nrows(self):
         return self._nrows
     ncols = nrows