hmc.py 文件源码

def metropolis_hastings_accept(energy_prev, energy_next, s_rng):
    """
    Performs a Metropolis-Hastings accept-reject move.

    Parameters
    ----------
    energy_prev: theano vector
        Symbolic theano tensor which contains the energy associated with the
        configuration at time-step t.
    energy_next: theano vector
        Symbolic theano tensor which contains the energy associated with the
        proposed configuration at time-step t+1.
    s_rng: theano.tensor.shared_randomstreams.RandomStreams
        Theano shared random stream object used to generate the random number
        used in proposal.

    Returns
    -------
    return: boolean
        True if move is accepted, False otherwise
    """
    ediff = energy_prev - energy_next
    return (TT.exp(ediff) - s_rng.uniform(size=energy_prev.shape)) >= 0