X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=mjo%2Feja%2Feja_algebra.py;h=9b028809c6ca46efd13d974fd99b176d1761754e;hb=257faa05a58651e2fbad0545c6413cc3e9203539;hp=832e7a19d5857fcd429a11b8693565aa781ba617;hpb=02c754829b2f2e8378561e6afd7cbfab2577f3f4;p=sage.d.git diff --git a/mjo/eja/eja_algebra.py b/mjo/eja/eja_algebra.py index 832e7a1..9b02880 100644 --- a/mjo/eja/eja_algebra.py +++ b/mjo/eja/eja_algebra.py @@ -9,10 +9,11 @@ from sage.algebras.quatalg.quaternion_algebra import QuaternionAlgebra from sage.categories.magmatic_algebras import MagmaticAlgebras from sage.combinat.free_module import CombinatorialFreeModule from sage.matrix.constructor import matrix +from sage.matrix.matrix_space import MatrixSpace from sage.misc.cachefunc import cached_method from sage.misc.prandom import choice from sage.misc.table import table -from sage.modules.free_module import VectorSpace +from sage.modules.free_module import FreeModule, VectorSpace from sage.rings.integer_ring import ZZ from sage.rings.number_field.number_field import QuadraticField from sage.rings.polynomial.polynomial_ring_constructor import PolynomialRing @@ -207,8 +208,13 @@ class FiniteDimensionalEuclideanJordanAlgebra(CombinatorialFreeModule): determinant). """ z = self._a_regular_element() - V = self.vector_space() - V1 = V.span_of_basis( (z**k).to_vector() for k in range(self.rank()) ) + # Don't use the parent vector space directly here in case this + # happens to be a subalgebra. In that case, we would be e.g. + # two-dimensional but span_of_basis() would expect three + # coordinates. + V = VectorSpace(self.base_ring(), self.vector_space().dimension()) + basis = [ (z**k).to_vector() for k in range(self.rank()) ] + V1 = V.span_of_basis( basis ) b = (V1.basis() + V1.complement().basis()) return V.span_of_basis(b) @@ -263,7 +269,13 @@ class FiniteDimensionalEuclideanJordanAlgebra(CombinatorialFreeModule): # have multivatiate polynomial entries. names = tuple('X' + str(i) for i in range(1,n+1)) R = PolynomialRing(self.base_ring(), names) - V = self.vector_space().change_ring(R) + + # Using change_ring() on the parent's vector space doesn't work + # here because, in a subalgebra, that vector space has a basis + # and change_ring() tries to bring the basis along with it. And + # that doesn't work unless the new ring is a PID, which it usually + # won't be. + V = FreeModule(R,n) # Now let x = (X1,X2,...,Xn) be the vector whose entries are # indeterminates... @@ -503,11 +515,23 @@ class FiniteDimensionalEuclideanJordanAlgebra(CombinatorialFreeModule): """ if self._natural_basis is None: - return tuple( b.to_vector().column() for b in self.basis() ) + M = self.natural_basis_space() + return tuple( M(b.to_vector()) for b in self.basis() ) else: return self._natural_basis + def natural_basis_space(self): + """ + Return the matrix space in which this algebra's natural basis + elements live. + """ + if self._natural_basis is None or len(self._natural_basis) == 0: + return MatrixSpace(self.base_ring(), self.dimension(), 1) + else: + return self._natural_basis[0].matrix_space() + + @cached_method def one(self): """ @@ -698,6 +722,17 @@ class RealCartesianProductEJA(FiniteDimensionalEuclideanJordanAlgebra): sage: RealCartesianProductEJA(3, prefix='r').gens() (r0, r1, r2) + Our inner product satisfies the Jordan axiom:: + + sage: set_random_seed() + sage: n = ZZ.random_element(1,5) + sage: J = RealCartesianProductEJA(n) + sage: x = J.random_element() + sage: y = J.random_element() + sage: z = J.random_element() + sage: (x*y).inner_product(z) == y.inner_product(x*z) + True + """ def __init__(self, n, field=QQ, **kwargs): V = VectorSpace(field, n) @@ -1189,6 +1224,17 @@ class RealSymmetricEJA(FiniteDimensionalEuclideanJordanAlgebra): sage: RealSymmetricEJA(3, prefix='q').gens() (q0, q1, q2, q3, q4, q5) + Our inner product satisfies the Jordan axiom:: + + sage: set_random_seed() + sage: n = ZZ.random_element(1,5) + sage: J = RealSymmetricEJA(n) + sage: x = J.random_element() + sage: y = J.random_element() + sage: z = J.random_element() + sage: (x*y).inner_product(z) == y.inner_product(x*z) + True + """ def __init__(self, n, field=QQ, **kwargs): S = _real_symmetric_basis(n, field=field) @@ -1247,6 +1293,17 @@ class ComplexHermitianEJA(FiniteDimensionalEuclideanJordanAlgebra): sage: ComplexHermitianEJA(2, prefix='z').gens() (z0, z1, z2, z3) + Our inner product satisfies the Jordan axiom:: + + sage: set_random_seed() + sage: n = ZZ.random_element(1,5) + sage: J = ComplexHermitianEJA(n) + sage: x = J.random_element() + sage: y = J.random_element() + sage: z = J.random_element() + sage: (x*y).inner_product(z) == y.inner_product(x*z) + True + """ def __init__(self, n, field=QQ, **kwargs): S = _complex_hermitian_basis(n) @@ -1313,6 +1370,17 @@ class QuaternionHermitianEJA(FiniteDimensionalEuclideanJordanAlgebra): sage: QuaternionHermitianEJA(2, prefix='a').gens() (a0, a1, a2, a3, a4, a5) + Our inner product satisfies the Jordan axiom:: + + sage: set_random_seed() + sage: n = ZZ.random_element(1,5) + sage: J = QuaternionHermitianEJA(n) + sage: x = J.random_element() + sage: y = J.random_element() + sage: z = J.random_element() + sage: (x*y).inner_product(z) == y.inner_product(x*z) + True + """ def __init__(self, n, field=QQ, **kwargs): S = _quaternion_hermitian_basis(n) @@ -1375,6 +1443,17 @@ class JordanSpinEJA(FiniteDimensionalEuclideanJordanAlgebra): sage: JordanSpinEJA(2, prefix='B').gens() (B0, B1) + Our inner product satisfies the Jordan axiom:: + + sage: set_random_seed() + sage: n = ZZ.random_element(1,5) + sage: J = JordanSpinEJA(n) + sage: x = J.random_element() + sage: y = J.random_element() + sage: z = J.random_element() + sage: (x*y).inner_product(z) == y.inner_product(x*z) + True + """ def __init__(self, n, field=QQ, **kwargs): V = VectorSpace(field, n)