X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=mjo%2Feja%2Feja_algebra.py;h=ad619f667a853e191f254aa32aaed3664e27f6a5;hb=f85bca2ff71a537c82fae3736944ce8896c30251;hp=db1e63d1b56ade8d29a33d256ee7e1f2b5e97d31;hpb=6afd46c56380df3732f1dbe9e6ccc63ef77b6dd2;p=sage.d.git

diff --git a/mjo/eja/eja_algebra.py b/mjo/eja/eja_algebra.py
index db1e63d..ad619f6 100644
--- a/mjo/eja/eja_algebra.py
+++ b/mjo/eja/eja_algebra.py
@@ -3196,6 +3196,85 @@ class CartesianProductEJA(CombinatorialFreeModule_CartesianProduct,
         self.one.set_cache(self._cartesian_product_of_elements(ones))
         self.rank.set_cache(sum(J.rank() for J in algebras))
 
+    def _monomial_to_generator(self, mon):
+        r"""
+        Convert a monomial index into a generator index.
+
+        SETUP::
+
+            sage: from mjo.eja.eja_algebra import random_eja
+
+        TESTS::
+
+            sage: J1 = random_eja(field=QQ, orthonormalize=False)
+            sage: J2 = random_eja(field=QQ, orthonormalize=False)
+            sage: J = cartesian_product([J1,J2])
+            sage: all( J.monomial(m)
+            ....:      ==
+            ....:      J.gens()[J._monomial_to_generator(m)]
+            ....:      for m in J.basis().keys() )
+            True
+
+        """
+        # The superclass method indexes into a matrix, so we have to
+        # turn the tuples i and j into integers. This is easy enough
+        # given that the first coordinate of i and j corresponds to
+        # the factor, and the second coordinate corresponds to the
+        # index of the generator within that factor.
+        try:
+            factor = mon[0]
+        except TypeError: # 'int' object is not subscriptable
+            return mon
+        idx_in_factor = self._monomial_to_generator(mon[1])
+
+        offset = sum( f.dimension()
+                      for f in self.cartesian_factors()[:factor] )
+        return offset + idx_in_factor
+
+    def product_on_basis(self, i, j):
+        r"""
+        Return the product of the monomials indexed by ``i`` and ``j``.
+
+        This overrides the superclass method because here, both ``i``
+        and ``j`` will be ordered pairs.
+
+        SETUP::
+
+            sage: from mjo.eja.eja_algebra import (HadamardEJA,
+            ....:                                  JordanSpinEJA,
+            ....:                                  QuaternionHermitianEJA,
+            ....:                                  RealSymmetricEJA,)
+
+        EXAMPLES::
+
+            sage: J1 = JordanSpinEJA(2, field=QQ)
+            sage: J2 = RealSymmetricEJA(2, field=QQ, orthonormalize=False)
+            sage: J3 = HadamardEJA(1, field=QQ)
+            sage: K1 = cartesian_product([J1,J2])
+            sage: K2 = cartesian_product([K1,J3])
+            sage: list(K2.basis())
+            [e(0, (0, 0)), e(0, (0, 1)), e(0, (1, 0)), e(0, (1, 1)),
+            e(0, (1, 2)), e(1, 0)]
+            sage: g = K2.gens()
+            sage: (g[0] + 2*g[3]) * (g[1] - 4*g[2])
+            e(0, (0, 1)) - 4*e(0, (1, 1))
+
+        TESTS::
+
+            sage: J1 = RealSymmetricEJA(1,field=QQ)
+            sage: J2 = QuaternionHermitianEJA(1,field=QQ)
+            sage: J = cartesian_product([J1,J2])
+            sage: x = sum(J.gens())
+            sage: x == J.one()
+            True
+            sage: x*x == x
+            True
+
+        """
+        l = self._monomial_to_generator(i)
+        m = self._monomial_to_generator(j)
+        return FiniteDimensionalEJA.product_on_basis(self, l, m)
+
     def matrix_space(self):
         r"""
         Return the space that our matrix basis lives in as a Cartesian
@@ -3447,3 +3526,16 @@ class RationalBasisCartesianProductEJA(CartesianProductEJA,
 RationalBasisEJA.CartesianProduct = RationalBasisCartesianProductEJA
 
 random_eja = ConcreteEJA.random_instance
+
+# def random_eja(*args, **kwargs):
+#     J1 = ConcreteEJA.random_instance(*args, **kwargs)
+
+#     # This might make Cartesian products appear roughly as often as
+#     # any other ConcreteEJA.
+#     if ZZ.random_element(len(ConcreteEJA.__subclasses__()) + 1) == 0:
+#         # Use random_eja() again so we can get more than two factors.
+#         J2 = random_eja(*args, **kwargs)
+#         J = cartesian_product([J1,J2])
+#         return J
+#     else:
+#         return J1