Embed the points using spectral decomposition of the laplacian of
        the affinity matrix

        Parameters
        ----------
        n:      int
                The number of dimensions

def spectral_embedding(self, n):
        """
        Embed the points using spectral decomposition of the laplacian of
        the affinity matrix

        Parameters
        ----------
        n:      int
                The number of dimensions
        """
        coords = spectral_embedding(self._affinity, n)
        return CoordinateMatrix(normalise_rows(coords))