Revert "eja: drop custom _is_commutative() in favor of is_commutative()."

[sage.d.git] / mjo / eja / eja_algebra.py

diff --git a/mjo/eja/eja_algebra.py b/mjo/eja/eja_algebra.py
index c6a82caa9cf74ba78d44fe0db88668805d973e44..af7d059631b1706227e59d54952cfec552ddabb1 100644 (file)
--- a/mjo/eja/eja_algebra.py
+++ b/mjo/eja/eja_algebra.py
@@ -178,7 +178,8 @@ class FiniteDimensionalEJA(CombinatorialFreeModule):
 
 
         category = MagmaticAlgebras(field).FiniteDimensional()
-        category = category.WithBasis().Unital()
+        category = category.WithBasis().Unital().Commutative()
+
         if associative:
             # Element subalgebras can take advantage of this.
             category = category.Associative()
@@ -422,6 +423,18 @@ class FiniteDimensionalEJA(CombinatorialFreeModule):
         """
         return "Associative" in self.category().axioms()
 
+    def _is_commutative(self):
+        r"""
+        Whether or not this algebra's multiplication table is commutative.
+
+        This method should of course always return ``True``, unless
+        this algebra was constructed with ``check_axioms=False`` and
+        passed an invalid multiplication table.
+        """
+        return all( self.product_on_basis(i,j) == self.product_on_basis(i,j)
+                    for i in range(self.dimension())
+                    for j in range(self.dimension()) )
+
     def _is_jordanian(self):
         r"""
         Whether or not this algebra's multiplication table respects the
@@ -429,7 +442,7 @@ class FiniteDimensionalEJA(CombinatorialFreeModule):
 
         We only check one arrangement of `x` and `y`, so for a
         ``True`` result to be truly true, you should also check
-        :meth:`is_commutative`. This method should of course always
+        :meth:`_is_commutative`. This method should of course always
         return ``True``, unless this algebra was constructed with
         ``check_axioms=False`` and passed an invalid multiplication table.
         """
@@ -448,11 +461,14 @@ class FiniteDimensionalEJA(CombinatorialFreeModule):
         this algebra was constructed with ``check_axioms=False`` and
         passed an invalid Jordan or inner-product.
         """
+        R = self.base_ring()
 
-        # Used to check whether or not something is zero in an inexact
-        # ring. This number is sufficient to allow the construction of
-        # QuaternionHermitianEJA(2, field=RDF) with check_axioms=True.
-        epsilon = 1e-16
+        # Used to check whether or not something is zero.
+        epsilon = R.zero()
+        if not R.is_exact():
+            # This choice is sufficient to allow the construction of
+            # QuaternionHermitianEJA(2, field=RDF) with check_axioms=True.
+            epsilon = 1e-15
 
         for i in range(self.dimension()):
             for j in range(self.dimension()):
@@ -462,12 +478,8 @@ class FiniteDimensionalEJA(CombinatorialFreeModule):
                     z = self.gens()[k]
                     diff = (x*y).inner_product(z) - x.inner_product(y*z)
 
-                    if self.base_ring().is_exact():
-                        if diff != 0:
-                            return False
-                    else:
-                        if diff.abs() > epsilon:
-                            return False
+                    if diff.abs() > epsilon:
+                        return False
 
         return True
 
@@ -1776,9 +1788,9 @@ class RealSymmetricEJA(ConcreteEJA, RealMatrixEJA):
 
     In theory, our "field" can be any subfield of the reals::
 
-        sage: RealSymmetricEJA(2, field=RDF)
+        sage: RealSymmetricEJA(2, field=RDF, check_axioms=True)
         Euclidean Jordan algebra of dimension 3 over Real Double Field
-        sage: RealSymmetricEJA(2, field=RR)
+        sage: RealSymmetricEJA(2, field=RR, check_axioms=True)
         Euclidean Jordan algebra of dimension 3 over Real Field with
         53 bits of precision
 
@@ -2044,9 +2056,9 @@ class ComplexHermitianEJA(ConcreteEJA, ComplexMatrixEJA):
 
     In theory, our "field" can be any subfield of the reals::
 
-        sage: ComplexHermitianEJA(2, field=RDF)
+        sage: ComplexHermitianEJA(2, field=RDF, check_axioms=True)
         Euclidean Jordan algebra of dimension 4 over Real Double Field
-        sage: ComplexHermitianEJA(2, field=RR)
+        sage: ComplexHermitianEJA(2, field=RR, check_axioms=True)
         Euclidean Jordan algebra of dimension 4 over Real Field with
         53 bits of precision
 
@@ -2341,9 +2353,9 @@ class QuaternionHermitianEJA(ConcreteEJA, QuaternionMatrixEJA):
 
     In theory, our "field" can be any subfield of the reals::
 
-        sage: QuaternionHermitianEJA(2, field=RDF)
+        sage: QuaternionHermitianEJA(2, field=RDF, check_axioms=True)
         Euclidean Jordan algebra of dimension 6 over Real Double Field
-        sage: QuaternionHermitianEJA(2, field=RR)
+        sage: QuaternionHermitianEJA(2, field=RR, check_axioms=True)
         Euclidean Jordan algebra of dimension 6 over Real Field with
         53 bits of precision