def _trace(self):
# The diagonal of the [[nested] block] circulant operator is the mean of
# the spectrum.
# Proof: For the [0,...,0] element, this follows from the IDFT formula.
# Then the result follows since all diagonal elements are the same.
# Therefore, the trace is the sum of the spectrum.
# Get shape of diag along with the axis over which to reduce the spectrum.
# We will reduce the spectrum over all block indices.
if tensor_shape.TensorShape(self.spectrum.shape).is_fully_defined():
spec_rank = tensor_shape.TensorShape(self.spectrum.shape).ndims
axis = np.arange(spec_rank - self.block_depth, spec_rank, dtype=np.int32)
else:
spec_rank = array_ops.rank(self.spectrum)
axis = math_ops.range(spec_rank - self.block_depth, spec_rank)
# Real diag part "re_d".
# Suppose tensor_shape.TensorShape(spectrum.shape) = [B1,...,Bb, N1, N2]
# tensor_shape.TensorShape(self.shape) = [B1,...,Bb, N, N], with N1 * N2 = N.
# tensor_shape.TensorShape(re_d_value.shape) = [B1,...,Bb]
re_d_value = math_ops.reduce_sum(math_ops.real(self.spectrum), axis=axis)
if not np.issubdtype(self.dtype, np.complexfloating):
return _ops.cast(re_d_value, self.dtype)
# Imaginary part, "im_d".
if self.is_self_adjoint:
im_d_value = array_ops.zeros_like(re_d_value)
else:
im_d_value = math_ops.reduce_sum(math_ops.imag(self.spectrum), axis=axis)
return _ops.cast(math_ops.complex(re_d_value, im_d_value), self.dtype)
def assert_zero_imag_part(x, message=None, name="assert_zero_imag_part"):
"""Returns `Op` that asserts Tensor `x` has no non-zero imaginary parts.
Args:
x: Numeric `Tensor`, real, integer, or complex.
message: A string message to prepend to failure message.
name: A name to give this `Op`.
Returns:
An `Op` that asserts `x` has no entries with modulus zero.
"""
with ops.name_scope(name, values=[x]):
x = ops.convert_to_tensor(x, name="x")
dtype = x.dtype
if dtype.is_floating:
return control_flow_ops.no_op()
zero = ops.convert_to_tensor(0, dtype=dtypes.real_dtype(dtype))
return check_ops.assert_equal(zero, math_ops.imag(x), message=message)
def assert_hermitian_spectrum(self, name="assert_hermitian_spectrum"):
"""Returns an `Op` that asserts this operator has Hermitian spectrum.
This operator corresponds to a real-valued matrix if and only if its
spectrum is Hermitian.
Args:
name: A name to give this `Op`.
Returns:
An `Op` that asserts this operator has Hermitian spectrum.
"""
eps = np.finfo(dtypes.real_dtype(self.dtype)).eps
with self._name_scope(name): # pylint: disable=not-callable
# Assume linear accumulation of error.
max_err = eps * self.domain_dimension_tensor()
imag_convolution_kernel = math_ops.imag(self.convolution_kernel())
return check_ops.assert_less(math_ops.abs(imag_convolution_kernel),
max_err,
message="Spectrum was not Hermitian")
def _assert_self_adjoint(self):
imag_multiplier = math_ops.imag(self.multiplier)
return check_ops.assert_equal(
array_ops.zeros_like(imag_multiplier),
imag_multiplier,
message="LinearOperator was not self-adjoint")
