Pablo Piskunow authored Feb 10, 2017 and Joseph Weston committed Feb 16, 2017

Now, the tolerance to which the spectral bounds of the Hamiltonian
are calculated is set by 'epsilon', which also controls the
rescaling of the Hamiltonian to ensure that the spectral bounds are
strictly between (-1, 1). Also the spectral bounds are only calculated
*once* (if not provided by the user).