Spectrum

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   

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.

     

def _shape(self):
    s_shape = self._spectrum.shape
    # Suppose spectrum.shape = [a, b, c, d]
    # block_depth = 2
    # Then:
    #   batch_shape = [a, b]
    #   N = c*d
    # and we want to return
    #   [a, b, c*d, c*d]
    batch_shape = s_s