def get_array(self, indexed):
""" Return an array of LeviCivita objects comprising the appropriate indices given in the user's equations. """
array = MutableDenseNDimArray.zeros(*indexed.shape)
for index in numpy.ndindex(*indexed.shape):
array[index[:]] = LeviCivita(*index)
return array
def get_array(self, indexed, args=None):
""" Return an array of Indexed/EinsteinTerm objects.
:arg sympy.Indexed indexed: A SymPy Indexed term.
:arg args: A tuple of arguments to be provided to a function (e.g. the LeviCivita function). By default this is None.
:returns: An array of Indexed/EinsteinTerm objects
:rtype: sympy.MutableDenseNDimArray, if it has indices else Einstein Term will be returned
"""
if len(self.get_indices()) == 0:
value = self
value.is_commutative = True
if args:
array = IndexedBase('%s' % value)[args]
else:
array = value
return array
array = MutableDenseNDimArray.zeros(*indexed.shape)
from_indices = indexed.indices
for index in numpy.ndindex(*indexed.shape):
index_map = self.map_indices(from_indices, index)
value = self.get_expanded(index_map)
value.is_commutative = True
if args:
# If this is a function such as the Levi-Civita function, then it will have arguments (e.g. x0, x1, t) which need to be included here.
array[index] = IndexedBase('%s' % value)[args]
else:
array[index] = value
return array
def get_indexed(self, ndim, indexed, arrays, new_array_name):
derivative_function = self.args[0]
base = IndexedBase('%s' % derivative_function)
evaluated, index_structure = evaluate_expression(
derivative_function, arrays, indexed)
if index_structure:
derivative_structure = index_structure
functions = [base[index_structure]]
else:
derivative_structure = []
functions = [base]
for arg in self.args[1:]:
derivative_structure = derivative_structure + list(
indexed[arg].indices)
functions.append(indexed[arg])
shape = []
for number, index in enumerate(derivative_structure):
if isinstance(index, Idx):
shape += [ndim]
else:
shape += [index]
# Fill an array of the same shape as the derivative structure with the actual SymPy Derivative objects.
derivative = MutableDenseNDimArray.zeros(*shape)
for index in numpy.ndindex(*shape):
index_map = self.split_index(index, functions)
derivative[index] = self.apply_derivative(index_map, arrays,
functions, evaluated)
# Apply the contraction structure
outer_indices = remove_repeated_index(derivative_structure)
if derivative_structure:
derivative = apply_contraction(outer_indices, derivative_structure,
derivative)
if outer_indices:
new_outer_indices = [
outer for outer in outer_indices if outer != 1
]
if new_outer_indices == outer_indices:
indexed_object_name = IndexedBase(
new_array_name, shape=tuple([ndim for x in outer_indices
]))[tuple(outer_indices)]
else:
raise ValueError("Indices do not match: ", new_outer_indices,
outer_indices)
indexed_object_name.is_commutative = False
indexed[self] = indexed_object_name
arrays[indexed_object_name] = derivative
else:
indexed_object_name = EinsteinTerm(new_array_name)
indexed[self] = indexed_object_name
arrays[indexed_object_name] = derivative
return arrays, indexed
